Method for extracting scandium from titanium white waste acid by utilizing diphosphonic acid extraction agent

Abstract

The invention belongs to the technical field of extraction of scandium and diphosphonic acid extraction agents from titanium dioxide waste acid, and particularly relates to a method for extracting scandium from titanium dioxide waste acid by using a diphosphonic acid extraction agent. A scandium extraction extracting agent commonly used in titanium white waste acid generally has the problems of relatively poor selectivity, easiness in emulsification, difficulty in reverse extraction and the like. According to the method, P, P '-[(imine) bis (methylene) bis [P-alpha-hydroxyalkylphosphinic acid] is adopted as an extracting agent, trace scandium is extracted from the high-acidity titanium white waste acid, and the single extraction rate reaches 99.9%. The extraction agent is simple in synthesis method, good in stability and high in extraction capacity, and has good extraction performance on trace scandium in high-acidity and multi-impurity titanium white waste acid. The extraction agent is free of emulsification during extraction, fast in phase splitting and high in production efficiency, and compared with common phosphorus (phosphine) extraction agents, the extraction agent does not need saponification and belongs to an environment-friendly extraction agent.

Description

Technical Field

[0001] The invention belongs to the technical field of solution extraction, and in particular relates to a method for extracting scandium from titanium dioxide waste acid by using a diphosphonic acid extractant. Background Art

[0002] Scandium is difficult to enrich in nature to form independent scandium minerals, and is often associated with other minerals. Its recycling process is complex, the recovery rate is low, and the cost is high, making scandium one of the most expensive metals in the world. The lack of reliable supply and high production costs have hindered the application of scandium in high-end technologies to a certain extent. Therefore, it is crucial to seek large quantities of cheap recycled scandium raw materials.

[0003] The production of titanium dioxide in my country's titanium dioxide industry is still mainly based on the sulfuric acid method. The industry produces a total of about 8,000 kt / a of waste acid. The average mass concentration of Sc in titanium dioxide waste acid is about 10-20 mg / L, which is a good secondary resource rich in scandium. However, the sulfuric acid concentration of titanium dioxide waste acid is high, and the types of impurity metal elements are many and the content is much higher than the content of scandium, which makes recovery and purification very difficult. At present, the main technology for recovering scandium from titanium dioxide waste acid is solvent extraction. "A method for extracting scandium from coal gangue by concentrated sulfuric acid activation leaching" (CN109777972A) uses primary amine N1923 extractant to extract scandium from ore pulp leachate. However, alkaline amine extractants are easy to emulsify and difficult to stratify, and are not suitable for extracting scandium from titanium dioxide waste acid. "A method for recovering scandium from titanium dioxide waste acid" (CN103614560B) uses 20% P204+75TBP+73% sulfonated kerosene as an organic phase to extract scandium from titanium dioxide waste acid, then uses a mixed acid wash liquid to wash the impurity elements in the organic phase, and then uses a C l - Alkaline solution is used for stripping to generate hydroxide precipitate, which is filtered and calcined to obtain scandium oxide powder with a purity higher than 95%. "A method for preparing high-purity scandium by one-step neutralization of titanium dioxide waste acid with carbide slag" (CN105200248B) uses saponified P204 to extract scandium from Fe and Al concentrates, with a recovery rate of more than 80%. P204 needs to be saponified when used, has poor selectivity for scandium, and is difficult to strip. Therefore, it is necessary to design an extractant that has good extraction performance for scandium ions in titanium dioxide waste acid with high acidity, high impurities, and low scandium content. Summary of the invention

[0004] The commonly used extractants for extracting scandium from titanium dioxide waste acid generally have the problems of low selectivity, easy emulsification, and easy occurrence of three phases, which greatly limits its large-scale industrial application. The present invention studies the extraction of trace scandium in titanium dioxide waste acid by P,P'-[(imine)bis(methylene)bis[P-α-hydroxyalkylphosphinic acid] extractant. By changing the extraction conditions, it is found that the extractant has a good extraction effect on scandium in titanium dioxide waste acid with high acidity. Under the optimal extraction conditions, the extraction rate reaches 99.9%.

[0005] The present invention adopts a method for extracting scandium from titanium dioxide waste acid using a bisphosphonic acid extractant, and is carried out according to the following steps:

[0006] (1) Use titanium dioxide waste acid as the aqueous phase.

[0007] (2) A bisphosphonic acid extractant prepared with a diluent and a phase regulator is used as an organic phase.

[0008] (3) The aqueous phase and the organic phase are mixed and extracted, and the mixed solution after extraction is separated into phases to obtain an organic phase loaded with scandium and a raffinate containing other metal elements.

[0009] (4) The organic phase loaded with scandium ions is stripped with a stripping agent to obtain an aqueous solution containing scandium ions.

[0010] Wherein, Sc in the aqueous phase 3+ The concentration is 0.001-1 g / L, and the sulfuric acid concentration is 0.01-5 mol / L. The structure of the bisphosphonic acid extractant is shown in Formula 1, wherein R1 and R2 are the same or different and are independently selected from substituted or unsubstituted C7-18 straight or branched alkyl groups.

[0011]

[0012] Formula 1: R1 and R2 represent alkyl chains

[0013] The diluent is one or more of aliphatic hydrocarbons, halogenated hydrocarbons, aromatic hydrocarbons, solvent oil and alcohol; preferably, the aliphatic hydrocarbon is one or more of n-hexane, cyclohexane and dodecane, and preferably, the halogenated hydrocarbon is one or more of dichloromethane, chloroform and 1,2-dichloroethane. Preferably, the aromatic hydrocarbon is one or more of toluene, xylene and 1,2,4-trimethylbenzene; preferably, the solvent oil is one or more of S-100 solvent oil, S-150 solvent oil and S-260 solvent oil, and preferably, the alcohol is n-octanol.

[0014] The ratio of the aqueous phase to the organic phase is 1:5 to 5:1.

[0015] The extraction time is 1 to 120 minutes, and the extraction temperature is 10 to 90°C.

[0016] The stripping agent is oxalic acid with a concentration of 0.1-2 mol / L, a stripping time of 10-120 minutes, a stripping temperature of 10-90°C, and the stripping agent can be reused after stripping.

[0017] Compared with the prior art, the present invention has the following characteristics and beneficial effects:

[0018] (1) The P,P'-[(imine)bis(methylene)bis[P-α-hydroxyalkylphosphinic acid] extractant of the present invention has simple synthesis, high yield, and can be produced on a large scale; the presence of the long-chain alkyl group ensures the oil solubility of the extractant, which can reduce the loss of the extractant during the extraction process.

[0019] (2) The present invention uses P,P'-[(imino)bis(methylene)bis[P-α-hydroxyalkylphosphinic acid] as an extractant, and it is found that the extraction performance of the extractant for scandium in titanium dioxide waste acid is significantly better than that of traditional phosphorus (phosphine) extractants such as P204, P507, and Cyanex272.

[0020] (3) The extractant used in the present invention has good thermal stability, is not easy to volatilize, and can be reused. All reagents used are low-priced and easy to obtain, and the input amount is small, which saves costs.

[0021] (4) The extractant used in the present invention has no emulsification phenomenon, has fast phase separation, and has high production efficiency.

[0022] (5) Compared with common phosphorus (phosphine) extractants, the extractant used in the present invention does not require saponification and is an environmentally friendly extractant. DETAILED DESCRIPTION

[0023] The extraction distribution ratio (D) and the extraction rate (E) can intuitively show the extraction ability of the extractant. D represents the ratio of the rare earth concentrations in the aqueous phase and the organic phase after extraction, and E represents the ratio of the scandium ion concentrations in the aqueous phase before and after extraction. The separation factor (β) is an important basis for reflecting the separation effect. β represents the ratio of the scandium distribution ratio to the distribution ratio of other metal elements. The concentration of rare earth in the present invention is determined by ICP-OES.

[0024] The present invention is described in detail below with reference to specific embodiments, but the protection scope of the present invention is not limited by the embodiments.

[0025] Example 1

[0026] Sc in water 3+The concentration is 1g / L, and the concentration of sulfuric acid is 3mol / L. 0.005mol / L of P,P'-[(octyl imine) di(methylene) di[P-α-hydroxyheptyl phosphinic acid], P,P'-[(dodecyl imine) di(methylene) di[P-α-hydroxyheptyl phosphinic acid], P,P'-[(hexadecyl imine) di(methylene) di[P-α-hydroxyheptyl phosphinic acid], P,P'-[(octadecyl imine) di(methylene) di[P-α-hydroxyheptyl phosphinic acid], P,P'-[(octadecyl imine) di(methylene) di[P-α-hydroxyheptyl phosphinic acid], P,P'-[(octadecyl imine) di(methylene) di[P-α-hydroxyheptyl phosphinic acid] or P,P'-[(octyl imine) di(methylene) di[P-α-hydroxyoctyl phosphinic acid] is prepared with a diluent and 20% n-octanol as the organic phase, and the diluent is S-260 solvent oil. 5 mL of the aqueous phase and the organic phase were mixed, the extraction time was 40 min, the extraction temperature was 35 °C, and the Sc in the raffinate was determined. 3+ The effects of the concentration of the extractant on the extraction rate are shown in Table 1.

[0027] Comparative Example

[0028] Sc in water 3+ The concentration is 1g / L, and the sulfuric acid concentration is 3mol / L. P204, P507, Cyanex 272, TOPO and TBP are prepared with 0.005mol / L of diluent and 20% n-octanol as organic phase, and the diluent is S-260 solvent oil. 5mL of aqueous phase and organic phase are mixed, the extraction time is 40min, the extraction temperature is 35℃, and the Sc in the raffinate is determined. 3+ The effects of the concentration of the extractant on the extraction rate are shown in Table 1.

[0029] Table 1

[0030]

[0031] Example 2

[0032] Sc in water 3+ The concentration is 1g / L, and the sulfuric acid concentration is 0, 1, 2, 3, 4 mol / L. Prepare 0.01 mol / L P,P'-[(octyl imine) di(methylene) di[P-α-hydroxyheptyl phosphinic acid] with diluent and 20% n-octanol as the organic phase, and the diluent is S-260 solvent oil. Take 5 mL of the aqueous phase and the organic phase respectively, mix them, extract for 30 minutes, extract at 25°C, and determine the Sc in the raffinate. 3+ The effect of sulfuric acid concentration on the extraction rate is shown in Table 2.

[0033] Table 2

[0034]

[0035] Example 3

[0036] Sc in water 3+ The concentration is 1g / L, and the sulfuric acid concentration is 3mol / L. Prepare 0.01mol / L P,P'-[(octyl imine) di(methylene) di[P-α-hydroxyheptyl phosphinate] with diluent and 20% n-octanol as the organic phase, and the diluent is S-260 solvent oil. Take 5mL of the aqueous phase and the organic phase respectively, and mix them. The extraction time is 2min, 5min, 10min, 20min, 30min, 40min, 50min, 60min, and the extraction temperature is 25℃. Determine the Sc in the raffinate 3+ The effects of concentration and time on the extraction rate are shown in Table 3.

[0037] Table 3

[0038]

[0039] Example 4

[0040] Sc in water 3+ The concentration is 0.001g / L, and the sulfuric acid concentration is 3mol / L. Prepare 0.01mol / L P,P'-[(octyl imine) di(methylene) di[P-α-hydroxyheptyl phosphinic acid] as the organic phase with diluent and 20% n-octanol. The diluents are cyclohexane, 1,2-dichloroethane, 1,2,4-trimethylbenzene, S-150 solvent oil and S-260 solvent oil. Take 5mL of each of the aqueous phase and the organic phase, mix them, extract for 10min, extract at 25℃, and determine the Sc in the raffinate. 3+ The effects of the concentration and diluent on the extraction rate are shown in Table 4.

[0041] Table 4

[0042]

[0043] Example 5

[0044] Sc in water 3+ The concentration is 1g / L, and the sulfuric acid concentration is 3mol / L. Prepare 0.01mol / L P,P'-[(octyl imine) di(methylene) di[P-α-hydroxyheptyl phosphinic acid] with diluent and 20% n-octanol as the organic phase, and the diluent is S-260 solvent oil. Take 5mL of the aqueous phase and the organic phase respectively, mix them, extract for 30min, and the extraction temperature is 25℃, 30℃, 40℃, 50℃, and determine the Sc in the raffinate. 3+ The effects of concentration and temperature on the extraction rate are shown in Table 5.

[0045] Table 5

[0046]

[0047] Example 6

[0048] Sc in water 3+ The concentration is 0.001g / L, and the sulfuric acid concentration is 3mol / L. Prepare 0.01mol / L, 0.05mol / L, 0.1mol / L, and 0.5mol / L of P,P'-[(octyl imine) di(methylene) di[P-α-hydroxyheptyl phosphinate] with diluent and 20% n-octanol as the organic phase, and the diluent is S-260 solvent oil. Take 5mL of the aqueous phase and the organic phase respectively, mix them, extract for 40min, extract at 25℃, and determine the Sc in the raffinate. 3+ The effects of the concentration and diluent on the extraction rate are shown in Table 6.

[0049] Table 6

[0050]

[0051] Example 7

[0052] Sc in water 3+ The concentration is 0.001g / L, and the sulfuric acid concentration is 3mol / L. Prepare 0.01mol / L P,P'-[(octyl imine) di(methylene) di[P-α-hydroxyheptyl phosphinic acid] with diluent and 20% n-octanol as the organic phase, and the diluent is S-260 solvent oil. Take 5mL of the aqueous phase and the organic phase respectively, mix them, extract for 40min, extract at 25℃, and determine the Sc in the raffinate. 3+ The concentration of Sc in the stripping water phase was determined by using 1 mol / L oxalic acid solution as the stripping agent, the stripping temperature was 25°C, and the stripping time was 10min, 30min, 50min, 60min, 80min, 100min, 150min, and 200min. 3+ The relationship between the concentration, stripping time and stripping rate is shown in Table 7.

[0053] Table 7

[0054]

[0055] Example 8

[0056] Sc in water 3+ The concentration is 0.001g / L, and the sulfuric acid concentration is 3mol / L. Prepare 0.01mol / L P,P'-[(octyl imine) di(methylene) di[P-α-hydroxyheptyl phosphinic acid] with diluent and 20% n-octanol as the organic phase, and the diluent is S-260 solvent oil. Take 5mL of the aqueous phase and the organic phase respectively, mix them, extract for 40min, extract at 25℃, and determine the Sc in the raffinate. 3+The concentration of Sc in the stripping water phase was determined by using 2 mol / L oxalic acid solution as the stripping agent, the stripping temperature was 25℃, 30℃, 40℃, 50℃, 60℃, and the stripping time was 60min. 3+ The relationship between the concentration, stripping temperature and stripping rate is shown in Table 8.

[0057] Table 8

[0058]

Claims

1. A method for extracting scandium from titanium dioxide waste acid using a bisphosphonic acid extractant, characterized in that The structure of the bisphosphoric acid extractant is shown in Formula 1, wherein R1 and R2 are the same or different and are independently selected from substituted or unsubstituted C7-18 straight chain or branched alkyl groups.

2. A method for extracting scandium from titanium dioxide waste acid using a bisphosphonic acid extractant, wherein the Sc in the titanium dioxide waste acid is 3+ The concentration is 0.001~1g / L, and the sulfuric acid concentration is 0.01~5mol / L; Features The following steps are involved: S1: a bisphosphonic acid extractant prepared with a diluent and a phase regulator as an organic phase, wherein the phase regulator is n-octanol, the bisphosphonic acid extractant is an extractant, and the concentration of the extractant is 0.01-0.5 mol / L; S2: mixing the aqueous phase with the organic phase, and separating the mixed solution after extraction to obtain an organic phase loaded with scandium ions and a raffinate; S3: stripping the organic phase loaded with scandium ions with a stripping agent at a stripping temperature of 20 to 80° C. to obtain an aqueous solution containing scandium ions.

3. A method for extracting scandium from titanium dioxide waste acid using a bisphosphonic acid extractant, characterized in that: In step S1, the diluent is one or more of aliphatic hydrocarbons, halogenated hydrocarbons, aromatic hydrocarbons, solvent oils and alcohols; preferably, the aliphatic hydrocarbons are one or more of n-hexane, cyclohexane and dodecane, and preferably, the halogenated hydrocarbons are one or more of dichloromethane, chloroform and 1,2-dichloroethane. Preferably, the aromatic hydrocarbons are one or more of toluene, xylene and 1,2,4-trimethylbenzene; preferably, the solvent oil is one or more of S-100 solvent oil, S-150 solvent oil and S-260 solvent oil, and preferably, the alcohol is n-octanol.

4. A method for extracting scandium from titanium dioxide waste acid using a bisphosphonic acid extractant according to claim 1, characterized in that: In the step S2, the ratio of the aqueous phase to the organic phase is 1:5 to 5:

1.

5. A method for extracting scandium from titanium dioxide waste acid using a bisphosphonic acid extractant according to claim 1, characterized in that: In step S2, the extraction time is 1 to 120 minutes, and the extraction temperature is 10 to 90°C.

6. A method for extracting scandium from titanium dioxide waste acid using a diphosphoric acid extractant according to claim 1, characterized in that: In step S3, the stripping agent is oxalic acid with a concentration of 0.1 to 1 mol / L, the stripping time is 10 to 120 min, and the stripping agent can be reused after stripping.

Images