Method for adding inhibitor in extraction and separation process of rare earth ions

Abstract

The invention provides a method for adding an inhibitor in the extraction and separation process of rare earth ions, and belongs to the technical field of rare earth hydrometallurgy. The preparation method comprises the following steps: weighing raw materials of the inhibitor in parts by mass, mixing the weighed raw materials, and sequentially heating, stirring and cooling to obtain the inhibitor; then according to the volume ratio, an inhibitor and an environment-friendly diluent are mixed to prepare an organic phase with a certain concentration, the organic phase is added to the last stage of a reverse extraction section or a saponification section, blank organic matter is saponified and then used for extraction separation of rare earth elements, and praseodymium chloride, neodymium chloride and praseodymium neodymium chloride series products with the rare earth impurity cerium reaching the standard are obtained. The method provided by the invention realizes green, efficient and low-cost extraction, separation and purification of praseodymium and neodymium series elements, and has important economic and social significance for promoting green and high-quality development of the rare earth industry.

Description

Technical Field

[0001] The invention relates to the technical field of rare earth hydrometallurgy, and in particular to a method for adding an inhibitor in the process of rare earth ion extraction and separation. Background Art

[0002] During the rare earth ion extraction and separation process, the main reason why the change of diluent leads to incomplete purification of the cerium component of the praseodymium-neodymium series products is that after the sulfonated kerosene with reducing properties is replaced by an environmentally friendly diluent, the reduction capacity of the extraction system is insufficient, and cerium (III) in the aqueous solution is converted to cerium (IV) during the saponification and extraction process. The easy extraction property of cerium (IV) leads to the break of the balance between cerium (III) and cerium (IV) in its aqueous solution, aggravating the trend of cerium (III) in the aqueous solution to cerium (IV) oxidation, resulting in the continuous accumulation of cerium (IV) in the organic phase, thus affecting the purification of the praseodymium-neodymium series products and the subsequent medium and heavy rare earths. The current operating process in the industry is the hydrogen peroxide reduction method, which uses H 2 O 2 The reduction characteristics under acidic conditions can eliminate the influence of cerium (IV), but due to H 2 O 2 It has strong oxidizing properties and high chemical activity. There are certain safety risks in its storage and use. 2 O 2 After being added, it is easy to decompose and produce HO free radicals. It has no selectivity for the oxidation of organic matter. No matter hydrocarbons, organic acids, phosphates, etc., they can be indiscriminately oxidized into small molecules, resulting in enhanced organic water solubility, decreased extraction capacity of organic extractants, increased organic consumption, increased phosphorus content in rare earth feed liquid, difficulty in removing impurities in subsequent precipitation process, high phosphorus content in products, increased COD content in wastewater, and many other problems.

[0003] Therefore, how to obtain a method for adding an inhibitor in the rare earth ion extraction and separation process to eliminate the adverse effects of cerium (IV) is a technical problem that needs to be solved at present. Summary of the invention

[0004] The purpose of the present invention is to provide a method for adding an inhibitor in the rare earth ion extraction and separation process, so as to solve the technical problems such as the decrease in the extraction capacity of the organic extractant, the increase in the phosphorus content in the feed solution, and the difficulty in the subsequent processing steps caused by the current hydrogen peroxide reduction method.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for adding an inhibitor in a rare earth ion extraction and separation process, comprising the following steps:

[0007] (1) weighing inhibitor raw materials according to their weight fractions, mixing the weighed raw materials, heating, stirring, and cooling them in sequence to obtain the inhibitor;

[0008] (2) According to the volume ratio, the inhibitor and the environmentally friendly diluent are mixed to prepare an organic phase of a certain concentration, and the organic phase is added to the last stage of the stripping section or the saponification section. The blank organic phase is used for extraction and separation of rare earth elements after saponification to obtain praseodymium chloride, neodymium chloride, and praseodymium-neodymium chloride series products with rare earth impurity cerium meeting the standard;

[0009] The inhibitor raw material comprises a main inhibitor, an auxiliary inhibitor and a diluent.

[0010] Furthermore, the main inhibitor comprises a hindered phenol compound, and the auxiliary inhibitor comprises a polyphenol hydroxy compound.

[0011] Furthermore, the mass ratio of the main inhibitor, the auxiliary inhibitor and the diluent is 5-40:1-30:80-110.

[0012] Furthermore, in the step (1), the heating temperature is 25 to 60° C., and the stirring time is 45 to 60 min.

[0013] Furthermore, in the step (1), the cooling temperature is 20 to 45°C.

[0014] Furthermore, the volume ratio of the inhibitor to the environmentally friendly diluent is 0.1-20:80-99.9.

[0015] Furthermore, the environmentally friendly diluent includes P507 environmentally friendly diluent.

[0016] Beneficial effects of the present invention:

[0017] The present invention can effectively inhibit and eliminate Ce(IV) in the extraction and separation process, inhibit the conversion of Ce(III) in the aqueous solution to Ce(IV) during saponification and extraction in the rare earth extraction and separation process, and eliminate Ce(IV) enriched in the organic phase in the rare earth extraction and separation process.

[0018] The present invention realizes the environmentally friendly, high-efficiency and low-cost extraction, separation and purification of praseodymium and neodymium series elements, has obvious prospects for industry promotion, and has important economic and social significance for promoting the green and high-quality development of my country's rare earth industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The figure is a simplified process flow diagram of the cerium-praseodymium separation process of the present invention. DETAILED DESCRIPTION

[0020] The present invention provides a method for adding an inhibitor in a rare earth ion extraction and separation process, comprising the following steps:

[0021] (1) weighing inhibitor raw materials according to their weight fractions, mixing the weighed raw materials, heating, stirring, and cooling them in sequence to obtain the inhibitor;

[0022] (2) According to the volume ratio, the inhibitor and the environmentally friendly diluent are mixed to prepare an organic phase of a certain concentration, and the organic phase is added to the last stage of the stripping section or the saponification section. The blank organic phase is used for extraction and separation of rare earth elements after saponification to obtain a series of praseodymium chloride and neodymium chloride products with the rare earth impurity cerium meeting the standard;

[0023] The inhibitor raw material comprises a main inhibitor, an auxiliary inhibitor and a diluent.

[0024] In the present invention, the main inhibitor is preferably a hindered phenol compound, and the auxiliary inhibitor is preferably a polyphenolic hydroxyl-containing compound.

[0025] In the present invention, the hindered phenol compound comprises one or more of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol, β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis(6-tert-butyl-4-methylphenol), 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis(4-tert-butyl-4-ethylphenol), 2,4,6-tri-tert-butylphenol, 4-hydroxy-3-tert-butyl-anisole, 2,6-di-tert-butyl-4-(dimethylaminomethyl)phenol, 4,4'-thiobis(2-tert-butyl-5-methylphenol), 4,4'-thiobis(6-tert-butyl-2-methylphenol) Several, preferably one or more of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] pentaerythritol ester, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl ester, 2,2'-methylenebis(6-tert-butyl-4-methylphenol), 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis-(4-tert-butyl-4-ethylphenol) and 2,4,6-tri-tert-butylphenol, further preferably one or more of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] pentaerythritol ester, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl ester and 2,2'-methylenebis(6-tert-butyl-4-methylphenol).

[0026] In the present invention, the polyphenol hydroxy compound comprises one or more of propyl gallate, pyrogallol, 1,3-di-tert-butyl-4,6-benzene, 3-butylcatechol, 4-butylcatechol, n-octylresorcinol, 5-pentylresorcinol, 4-propylresorcinol, tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, 2-methyl-5-sec-octadecyl-1,4-benzene, 4,6-di-tert-butylpyrogallol, 4-allylpyrogallol, 2-methyl-4-pentylpyrogallol and phenethylresorcinol, preferably propyl gallate, pyrogallol, 1,3-di-tert-butyl-4,6-benzene, 3-butylcatechol, 4-butylcatechol, n-octylresorcinol, 5-pentylresorcinol, 4-propylresorcinol, tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, 2-methyl-5-sec-octadecyl-1,4-benzene, 4,6-di-tert-butylpyrogallol, 4-allylpyrogallol, 2-methyl-4-pentylpyrogallol and phenethylresorcinol. One or more of propyl gallate, pyrogallol, 1,3-di-tert-butyl-4,6-benzene, 3-butylcatechol, 4-butylcatechol, n-octylresorcinol, 5-pentylresorcinol, 4-propylresorcinol, tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone and 2-methyl-5-sec-octadecyl-1,4-benzene, and more preferably one or more of propyl gallate, pyrogallol, 1,3-di-tert-butyl-4,6-benzene, 3-butylcatechol, 4-butylcatechol and n-octylresorcinol.

[0027] In the present invention, the diluent includes kerosene, 200# solvent oil, liquid paraffin, and straight-chain alkanes and aromatic hydrocarbons such as hexane and octane; the kerosene is preferably sulfonated kerosene, hydrogenated kerosene or aviation kerosene, mainly C11-C17 straight-chain alkanes; the 200# solvent oil is preferably C9-C12 alkanes; the liquid paraffin is preferably C15-C20 alkanes; the aromatic hydrocarbons are preferably toluene, xylene and Solvesso150 (a mixture of C9-C10 aromatic hydrocarbons, with a distillation range of 184-209°C, in which the aromatic hydrocarbon content is as high as 97%). The diluent is preferably one or more of sulfonated kerosene, hydrogenated kerosene, aviation kerosene, hexane, and liquid paraffin, and is further preferably one or more of hydrogenated kerosene, 200# solvent oil, and hexane.

[0028] In the present invention, the mass ratio of the main inhibitor, the auxiliary inhibitor and the diluent is 5-40:1-30:80-110, preferably 10-35:5-25:85-105, more preferably 15-30:10-20:90-100, and more preferably 20-25:12-18:90.

[0029] In the present invention, in the step (1), the heating temperature is 25 to 60° C., preferably 30 to 55° C., and more preferably 40 to 50° C.; the stirring time is 45 to 60 min, and preferably 50 to 55 min.

[0030] In the present invention, in the step (1), the cooling temperature is 20 to 45°C, preferably 25 to 35°C, and more preferably 30°C.

[0031] In the present invention, the volume ratio of the inhibitor to the environmentally friendly diluent is 0.1-20:80-99.9, preferably 5-15:85-95, more preferably 8-12:88-92, and more preferably 10:90.

[0032] In the present invention, the environmentally friendly diluent is preferably P507 environmentally friendly diluent.

[0033] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0034] The process flow of the industrial production line for extracting and separating cerium and praseodymium of the present invention is shown in Figure 1 , and its operating conditions are as follows:

[0035] The flow ratio condition is:

[0036] Organic phase: alkali solution: rare earth soap material: praseodymium-neodymium material solution: neodymium washing solution: back acid = 350±20: 37±2: 40±10: 60±10: 25±5: 35±10

[0037] Feed solution: concentration 1.8M, wherein the rare earth distribution La:Ce:PNS=27:52:21 (i.e. the distribution of cerium in the rare earth solution system is 52% of the total rare earth content)

[0038] Organic phase: concentrated 1.5M P507, diluent is environmentally friendly hydrogenated kerosene

[0039] Liquid caustic soda: concentration 6.0M

[0040] Stripping solution: 5.5M hydrochloric acid

[0041] Number of tank levels in each section:

[0042] Saponification stage: 2 levels

[0043] Rare earth soap segment: 4 levels

[0044] Extraction stage: 50 levels

[0045] Washing section: 40 levels

[0046] Stripping stage: 12 levels.

[0047] The extraction raw material is a mixed rare earth chloride solution. The production line belongs to the classic fractionation extraction model, which is composed of a saponification-rare earth soap section, an extraction section, a washing section, and a stripping section. The front end of the saponification-rare earth soap section introduces an unloaded P507 organic phase and sodium hydroxide soap base, and discharges saponification-rare earth soap wastewater. The feed liquid mixed with the rare earth chloride solution is introduced into the last stage of the extraction section in the middle part of the extraction generation line. The first stage of the extraction section discharges the purified lanthanum cerium chloride product, and part of it is returned to the end of the saponification-rare earth soap section for the preparation of an organic phase loaded with difficult-to-extract components, while the rare earth soap wastewater is discharged. High-concentration hydrochloric acid is introduced as a stripping agent at the last stage of the stripping section. The first stage of the stripping section discharges the purified praseodymium neodymium chloride product, and part of it is returned to the end of the washing section for washing and purifying the organic phase loaded with easy-to-extract components.

[0048] Example 1

[0049] (1) Weigh pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], propyl gallate and diluent No. 260 solvent oil in a mass ratio of 5:5:90, mix the weighed raw materials, stir for 0.5 h, then heat to 40° C. and continue stirring for 50 min. After the blending is completed, transfer the mixed material to a storage tank through an insulated pipe, cool to 20° C. and obtain an inhibitor;

[0050] (2) According to the volume ratio, the inhibitor and P507-environmentally friendly diluent are prepared in a volume ratio of 5:95 to prepare an organic phase with an inhibitor concentration of 5%, which is added to the last stage of the stripping section. The blank organic phase containing the inhibitor is returned from the end of the extraction production line to the head of the production line, and completes a cycle through the saponification-rare earth soap section, the extraction section, the washing section, and the stripping section. During the reciprocating process of the organic phase with the inhibitor added, it can significantly inhibit and eliminate Ce(IV) in the extraction system, thereby obtaining a series of praseodymium-neodymium chloride products with the rare earth impurity cerium meeting the standard.

[0051] Example 2

[0052] (1) Weigh β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate octadecyl ester, 1,3-di-tert-butyl-4,6-benzenediol and diluent No. 260 solvent oil according to the mass proportion of 5:5:90, mix the weighed raw materials and stir for 0.5 h, then heat to 50° C. and continue stirring for 50 min. After the blending is completed, transfer the mixed material to a storage tank through an insulated pipe, cool to 25° C. and obtain an inhibitor;

[0053] (2) According to the volume ratio, the inhibitor and P507-environmentally friendly diluent are prepared in a volume ratio of 1:99 to prepare an organic phase with an inhibitor concentration of 1%, and the organic phase is added to the last stage of the stripping section. The blank organic phase containing the inhibitor is returned from the end of the extraction production line to the head of the production line. The blank organic phase containing the inhibitor is used for extraction and separation of rare earth elements after saponification, thereby obtaining a series of praseodymium-neodymium chloride products with rare earth impurity cerium meeting the standard.

[0054] Example 3

[0055] (1) Weigh β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate octadecyl ester, 2,5-di-tert-butylhydroquinone and kerosene in a weight ratio of 8:12:100, mix the weighed raw materials, stir for 0.5 h, then heat to 60° C. and continue stirring for 50 min. After the blending is completed, transfer the mixed material to a storage tank through an insulated pipe, cool to 30° C. and obtain an inhibitor;

[0056] (2) According to the volume ratio, the inhibitor and P507-environmentally friendly diluent are prepared in a volume ratio of 8:92 to prepare an organic phase with an inhibitor concentration of 8%, and the organic phase is added to the last stage of the stripping section. The blank organic phase containing the inhibitor is returned from the end of the extraction production line to the head end of the production line. The blank organic phase containing the inhibitor is used for extraction and separation of rare earth elements after saponification, thereby obtaining a series of praseodymium-neodymium chloride products with rare earth impurity cerium meeting the standard.

[0057] Example 4

[0058] (1) Weigh β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate octadecyl ester, phenethyl resorcinol and cyclohexane in a weight ratio of 20:15:100, mix the weighed raw materials, stir for 0.5 h, then heat to 40° C. and continue stirring for 50 min. After the blending is completed, transfer the mixed material to a storage tank through an insulated pipe, cool to 20° C. and obtain an inhibitor;

[0059] (2) According to the volume ratio, the inhibitor and P507-environmentally friendly diluent are prepared in a volume ratio of 0.1:99.9 to prepare an organic phase with an inhibitor concentration of 0.1%, and the organic phase is added to the last stage of the stripping section. The blank organic phase containing the inhibitor is returned from the end of the extraction production line to the head end of the production line. The blank organic phase containing the inhibitor is used for extraction and separation of rare earth elements after saponification, thereby obtaining a series of praseodymium-neodymium chloride products with cerium as the rare earth impurity that meets the standard.

[0060] Example 5

[0061] (1) 2,2'-methylenebis(6-tert-butyl-4-methylphenol), 2-methyl-4-pentylphloroglucinol and cyclohexanone were weighed in a weight ratio of 18:22:100, the weighed raw materials were mixed and stirred for 0.5 h, then heated to 40° C. and stirred for 50 min. After the blending was completed, the mixed material was transferred to a storage tank through an insulated pipe, and the temperature was lowered to 20° C. to obtain an inhibitor;

[0062] (2) According to the volume ratio, the inhibitor and P507-environmentally friendly diluent are prepared in a volume ratio of 15:85 to prepare an organic phase with an inhibitor concentration of 15%, which is added to the saponification stage 1. After the blank organic phase containing the inhibitor is saponified, it goes through a saponification-rare earth soap stage, an extraction stage, a washing stage, and a stripping stage to complete a cycle. During the repeated circulation of the organic phase with the inhibitor added, it can significantly inhibit and eliminate Ce(IV) in the extraction system, thereby obtaining a series of praseodymium-neodymium chloride products with the rare earth impurity cerium meeting the standard.

[0063] Example 6

[0064] (1) 2,6-di-tert-butyl-p-cresol, 4-allylpyrogallol and No. 200 solvent oil were weighed in a mass ratio of 15:20:90, the weighed raw materials were mixed and stirred for 0.5 h, then heated to 50° C. and stirred for 50 min. After the blending was completed, the mixed material was transferred to a storage tank through an insulated pipe, and the temperature was lowered to 20° C. to obtain an inhibitor;

[0065] (2) According to the volume ratio, the inhibitor and P507-environmentally friendly diluent are prepared in a volume ratio of 20:80 to prepare an organic phase with an inhibitor concentration of 20%, which is added to the first stage of the saponification section. The blank organic phase containing the inhibitor is used to extract and separate the cerium and praseodymium elements to obtain a series of praseodymium and neodymium chloride products with the rare earth impurity cerium meeting the standard.

[0066] The wastewater separated from the extraction system with inhibitor added in Examples 1 to 6 which had been running for more than 30 days was tested, and the results are shown in Table 1 below:

[0067] Example 7

[0068] (1) 2,2'-methylenebis-(4-tert-butyl-4-ethylphenol), 4,6-di-tert-butylpyrogallol and liquid paraffin were weighed in a weight ratio of 10:15:80, the weighed raw materials were mixed and stirred for 1 hour, then heated to 35° C. and stirred for 50 minutes. After the blending was completed, the mixed material was transferred to a storage tank through an insulated pipe, and the temperature was lowered to 20° C. to obtain an inhibitor;

[0069] (2) According to the volume ratio, the inhibitor and P507-environmentally friendly diluent are prepared in a volume ratio of 18:82 to prepare an organic phase with an inhibitor concentration of 18%, which is added to the last stage of the extraction section. The blank organic phase containing the inhibitor is used to eliminate Ce(IV) in the organic phase, thereby obtaining a series of praseodymium-neodymium chloride products with the rare earth impurity cerium meeting the standard.

[0070] Example 8

[0071] (1) Weigh 4,4'-dithiodi(6-tert-butyl-2-methylphenol), 2-methyl-4-pentylphloroglucinol and kerosene in a mass ratio of 15:20:80, mix the weighed raw materials, stir for 1 hour, then heat to 45°C and continue stirring for 50 minutes. After the blending is completed, transfer the mixed material to a storage tank through an insulated pipe, cool to 30°C and obtain an inhibitor;

[0072] (2) According to the volume ratio, the inhibitor and P507-environmentally friendly diluent are prepared in a volume ratio of 12:88 to prepare an organic phase with an inhibitor concentration of 12%, which is added to the last stage of the extraction section. The blank organic phase containing the inhibitor is used to eliminate Ce(IV) in the organic phase, thereby obtaining a series of praseodymium-neodymium chloride products with the rare earth impurity cerium meeting the standard.

[0073] The wastewater separated from the extraction system with inhibitor added in Examples 1 to 8 which had been running for more than 30 days was tested, and the results are shown in Table 1 below:

[0074] Table 1 Test results

[0075] Cerium content in praseodymium-neodymium series rare earth chloride products Example 1 ≤100ppm Example 2 ≤100ppm Example 3 ≤100ppm Example 4 ≤100ppm Example 5 ≤100ppm Example 6 ≤100ppm Example 7 ≤100ppm Example 8 ≤100ppm

[0076] As can be seen from the above embodiments, the present invention provides a method for adding an inhibitor in the process of rare earth ion extraction and separation. The present invention prepares an organic phase with a certain concentration of an inhibitor and a diluent, and the organic phase is added from the head of the extraction production line or the end of the stripping section, and a cycle is completed through the saponification-rare earth soap section, the extraction section, the washing section, and the stripping section. The organic phase with the inhibitor added can play a significant inhibitory and elimination role on cerium (IV) in the extraction system during the reciprocating cycle, thereby ensuring the qualified cerium in the praseodymium-neodymium series products.

[0077] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for adding an inhibitor in a rare earth ion extraction and separation process, characterized in that: The following steps are involved: (1) weighing inhibitor raw materials according to their weight fractions, mixing the weighed raw materials, heating, stirring, and cooling them in sequence to obtain the inhibitor; (2) According to the volume ratio, the inhibitor and the environmentally friendly diluent are mixed to prepare an organic phase of a certain concentration, and the organic phase is added to the last stage of the stripping section or the saponification section. The blank organic phase is used for extraction and separation of rare earth elements after saponification to obtain praseodymium chloride, neodymium chloride, and praseodymium-neodymium chloride series products with rare earth impurity cerium meeting the standard; The inhibitor raw material comprises a main inhibitor, an auxiliary inhibitor and a diluent.

2. The method for adding an inhibitor in the rare earth ion extraction and separation process according to claim 1, characterized in that: The main inhibitor comprises a hindered phenol compound, and the auxiliary inhibitor comprises a polyphenolic hydroxyl compound.

3. The method for adding an inhibitor in the rare earth ion extraction and separation process according to claim 1 or 2, characterized in that: The mass ratio of the main inhibitor, the auxiliary inhibitor and the diluent is 5-40:1-30:80-110.

4. The method for adding an inhibitor in the rare earth ion extraction and separation process according to claim 3, characterized in that: In the step (1), the heating temperature is 25 to 60° C. and the stirring time is 45 to 60 min.

5. The method for adding an inhibitor in the rare earth ion extraction and separation process according to claim 1 or 4, characterized in that: In the step (1), the cooling temperature is 20 to 45°C.

6. The method for adding an inhibitor in the rare earth ion extraction and separation process according to claim 5, characterized in that: The volume ratio of the inhibitor to the environmentally friendly diluent is 0.1-20:80-99.

9.

7. The method for adding an inhibitor in the rare earth ion extraction and separation process according to claim 1, 2 or 6, characterized in that: The environmentally friendly diluent includes P507 environmentally friendly diluent.

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