A method for removing chlorine from zinc electrolyte

Abstract

This invention relates to a method for extracting and removing chlorine from zinc electrolyte, using an amino-containing neutral phosphine extractant of Formula I to extract and remove chlorine from a chlorine-containing zinc sulfate solution. The amino-containing neutral phosphine extractant has low water solubility, a simple synthesis route, low cost, excellent chlorine extraction ability, high treatment efficiency, low wastewater volume, and low loss during recycling, thus effectively reducing chlorine removal costs and possessing high industrial application value. (I)

Description

Technical Field

[0001] This invention relates to the field of chloride ion extraction and separation technology, and specifically to a method for extracting and removing chloride from zinc electrolyte. Background Technology

[0002] In hydrometallurgical zinc smelting, a high chloride ion concentration in the zinc electrolyte severely impacts the electrolysis process. This not only significantly increases power consumption but also exacerbates corrosion of the lead anode plates, shortening their lifespan. Furthermore, dissolved lead is deposited at the cathode, reducing the zinc grade. When the chloride ion concentration reaches 800 ppm, chlorine gas is released from the anode, further affecting the zinc smelting environment. To ensure the quality of the cathode zinc and current efficiency, the chloride ion concentration in the solution must typically be controlled below 500 ppm. However, in some zinc raw material leaching solutions, the chloride content is much higher than this level, necessitating purification and dechlorination before electrolysis.

[0003] Industrial dechlorination methods mainly include precipitation, ion exchange, ozone oxidation, and adsorption. Precipitation is costly and incomplete. Ion exchange results in high zinc loss and generates large amounts of chlorine-containing wastewater. Ozone oxidation requires high solution acidity and releases chlorine gas and incompletely reacted ozone, significantly impacting the working environment. Adsorption methods use expensive dechlorinating agents, and some agents can interfere with zinc deposition during the electrolysis process.

[0004] Extraction methods have the advantages of high dechlorination efficiency, simple process and convenient operation. However, N235 is often used as the extractant for dechlorination at present. CN103060561A discloses a method for dechlorinating zinc sulfate solution containing chlorine using trialkyl tertiary amine N235. However, trialkyl tertiary amine is easy to emulsify and difficult to separate phases, so alcohol phase modifiers need to be added.

[0005] Therefore, developing extractants with better chlorine extraction capabilities, good extraction phenomena, and stable properties compared to N235, as well as extraction methods for chlorine removal, is of great significance for the purification and dechlorination of zinc electrolytes. Summary of the Invention

[0006] The inventors of this invention have developed a method for extracting and separating thorium, cerium, zirconium, hafnium, uranium, copper, indium, and gallium using an amino-containing neutral phosphine extractant, as detailed in CN 105734289 A, CN 105734288 A, CN 107287419 A, CN106521190 A, CN 106521153 A, CN 107674974 A, and CN 109097570 A. The inventors applied the amino-containing neutral phosphine extractant to remove chloride ions from zinc sulfate electrolyte, achieving good results, thus completing this invention. The amino-containing neutral phosphine extractant used is stable, easy to synthesize, and has low water solubility. The significant feature of this invention is that, compared with the tertiary amine extractant N235, the use of amino-containing neutral phosphine as the extractant results in excellent extraction, a clear phase interface, rapid phase separation, and eliminates the need for phase modifiers. It can easily reduce the chloride ion content in zinc electrolyte to below 300 ppm. Therefore, this invention has significant advantages in treating chloride-containing zinc electrolytes.

[0007] This invention provides the use and method of using an amino-containing neutral phosphine extractant of Formula I for the extraction and removal of chlorine from a chlorine-containing zinc sulfate solution:

[0008] (I)

[0009] in,

[0010] R1 and R2 are each independently selected from C1 to C2. 12 alkyl;

[0011] R3 and R4 are each independently selected from hydrogen, C1~C8 alkyl, C3~C 10 Alicyclic alkyl groups and C6~C 10 Aryl;

[0012] R5 and R6 are each independently selected from C1 to C2. 16 Alkyl groups and hydrogen, with at most one of R5 and R6 being hydrogen.

[0013] The method includes the step of removing chlorine from a chlorine-containing zinc sulfate solution by extracting it with an amino-containing neutral phosphine extractant of Formula I.

[0014] The method for removing chlorine by extraction according to the present invention can be carried out by solvent extraction, for example, by preparing the amino-containing neutral phosphine extractant of the present invention into a liquid extraction system for use.

[0015] Beneficial effects

[0016] The amino-containing neutral phosphine extractant used in this invention has low water solubility, a simple synthesis route, low cost, excellent chlorine extraction ability, high treatment efficiency, significantly reduced wastewater volume, and low loss during recycling, thus effectively reducing chlorine removal costs and having high industrial application value. Detailed Implementation

[0017] The present invention will now be described in detail, but the present invention is not limited to the following.

[0018] According to one aspect of the present invention, the use of the amino-containing neutral phosphine extractant of Formula I for the extraction and removal of chlorine from a chlorine-containing zinc sulfate solution is provided:

[0019] (I)

[0020] in,

[0021] R1 and R2 are each independently selected from C1 to C2. 12 Alkyl groups, preferably C2-C 10 Alkyl, more preferably C2-C9 alkyl, and most preferably C2-C8 alkyl;

[0022] R3 and R4 are each independently selected from hydrogen, C1~C8 alkyl, C3~C 10 Alicyclic alkyl groups and C6~C 10 Aryl group; preferably selected from hydrogen, C1-C6 alkyl, C3-C6 alicyclic alkyl and C6-C8 aryl groups;

[0023] R5 and R6 are each independently selected from C1 to C2. 16 Alkyl groups and hydrogen, with at most one of R5 and R6 being hydrogen.

[0024] In Formula I, R1 and R2 may be the same or different. Furthermore, R1 and R2 are preferably the same alkyl group, and more preferably the same C2 to C9 alkyl group.

[0025] Preferably, the total number of carbon atoms in R1 and R2 is an integer between 4 and 20, including but not limited to 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 and 20 carbon atoms, and preferably an integer between 4 and 18.

[0026] R3 and R4 may be the same or different. Preferably, R3 is selected from hydrogen, C1-C6 alkyl, C3-C6 alicyclic alkyl and C6-C8 aryl, preferably C1-C3 alkyl and hydrogen, more preferably methyl and hydrogen, and R4 is selected from C1-C6 alkyl, C3-C6 alicyclic alkyl, C6-C8 aryl and hydrogen, preferably C1-C3 alkyl and phenyl, more preferably methyl, ethyl and phenyl.

[0027] Preferably, the total number of carbon atoms in R3 and R4 is an integer between 0 and 12, including but not limited to 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12 carbon atoms, and is preferably an integer between 0 and 7.

[0028] R5 and R6 may be the same or different. Preferably, R5 is selected from C1 to C6. 10 Alkyl and hydrogen, preferably C1-C8 alkyl and hydrogen, R6 is selected from C1-C8. 14 Alkyl groups, preferably C1-C 12 Alkyl group. Preferably, the total number of carbon atoms in R5 and R6 is an integer between 1 and 24, including but not limited to 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, and 24 carbon atoms, and more preferably an integer between 2 and 20.

[0029] Preferably, in the amino-containing neutral phosphine extractant of Formula I of the present invention, the total number of carbon atoms of R1, R2, R3, R4, R5 and R6 is 10 to 48, including but not limited to 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47 and 48 carbon atoms, preferably 13 to 36, more preferably 15 to 34.

[0030] Preferably, the amino-containing neutral phosphine extractant of Formula I is one or more selected from the following compounds:

[0031]

[0032] The amino-containing neutral phosphine extractant of Formula I can be synthesized according to known or similar methods in the prior art (such as CN201410765062.1, CN201611012369.X).

[0033] According to another aspect of the present invention, a method for extracting and removing chlorine is provided, comprising the step of contacting an amino-containing neutral phosphine extractant of Formula I above with a chlorine-containing zinc sulfate solution to extract and remove chlorine from the chlorine-containing zinc sulfate solution.

[0034] In some embodiments, the extraction and dechlorination method of the present invention can be carried out by solvent extraction, the method comprising: mixing an organic phase containing an amino-containing neutral phosphine extractant of formula I with a chlorine-containing zinc sulfate solution to extract and obtain a chlorine-loaded organic phase and a chlorine-removing tail liquid.

[0035] Specifically, the solvent extraction method for dechlorination according to the present invention includes the following steps:

[0036] (1) Extraction: The chlorine-containing zinc sulfate solution is mixed with an organic phase containing an amino-containing neutral phosphine extractant of formula I for extraction to obtain a chlorine-loaded organic phase and a chlorine extraction tail liquid;

[0037] (2) Back-extraction: The organic phase loaded with chlorine is back-extracted with a back-extracting agent to obtain a back-extracting solution enriched with chlorine.

[0038] The organic phase comprises an amino-containing neutral phosphine extractant of Formula I, a non-essential auxiliary extractant, a non-essential phase modifier, and a diluent, specifically composed of the above-mentioned components. Here, "non-essential" means that the component may or may not be present, i.e., its content may be zero.

[0039] The auxiliary extractant mainly assists in extraction and can enhance the extraction performance of amino-containing neutral phosphine extractants for chlorine. The auxiliary extractant can be selected from neutral phosphorus (phosphine) extractants such as linear trialkylphosphine oxide (Cyanex 923), branched trialkylphosphine oxide (Cyanex 925), trioctylphosphine oxide (TOPO), dimethylheptyl methylphosphonate (P350), di(-2-ethylhexyl) 2-ethylhexylphosphonate, and tributyl phosphate (TBP); acidic phosphorus (phosphine) extractants such as di(2,4,4-trimethylpentyl)dithiophosphoic acid (Cyanex 301), di(2,4,4-trimethylpentyl)thiophosphoic acid (Cyanex 302), di(2-ethylhexyl)phosphophosphate (P204), mono-2-ethylhexyl 2-ethylhexylphosphoate (P507), di(2,4,4-trimethylpentyl)phosphoic acid (Cyanex 272), and di(2-ethylhexyl)phosphoic acid (P227 or P229); such as CN Neutral phosphoramide extractants disclosed in CN201410409451.0 and CN201410040023.5, such as triisooctylphosphamide, diisooctyl-isooctyloxyphosphamide, isooctyl-diisooctyloxyphosphamide, tris(diisobutyl)phosphamide, di(diisobutyl)-isooctyloxyphosphamide, tridecylphosphamide and dihexyl-decyloxyphosphamide, etc.; and mixed extractants of the above extractants in any proportion.

[0040] The phase modifier mainly functions to improve the physical phenomena of extraction, and it can be selected from C4~C6. 10 One or more of alkanols and tributyl phosphate (TBP), preferably one or more of n-octanol, isooctol, 2-methylheptanol, and a mixture of the above three alcohols in any proportion and tributyl phosphate; more preferably a mixture of alcohols or 2-methylheptanol.

[0041] The diluent is selected from: C5~C 16Alkanes, such as pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, etc.; aviation kerosene; sulfonated kerosene; liquid paraffin, such as light lubricating oil fractions at 250~400℃; C5~C 16 Alicyclic alkanes, such as cyclopentane, C1-C4 alkyl-substituted cyclopentane, cyclohexane, C1-C4 alkyl-substituted cyclohexane, decahydronaphthalene, etc.; C6-C 10 Aromatic hydrocarbons, such as benzene, toluene, xylene (including ortho-, meta-, para-xylene and mixed xylenes), etc. Preferably, the diluent is one or more selected from aviation kerosene, sulfonated kerosene, and heptane.

[0042] In the organic phase, the volume ratio of the amino-containing neutral phosphine extractant, the non-essential auxiliary extractant, the non-essential phase modifier, and the diluent of Formula I can be about 1~80: about 0~25: about 0~25: about 20~99, preferably about 10~75: about 0~20: about 0~20: about 25~90; more preferably about 15~60: 0~15: 0~15: 40~85.

[0043] The chlorine-containing zinc sulfate solution contains chlorine at a concentration of 100 ppm or more, preferably 300 ppm or more, and particularly 500 ppm or more.

[0044] The chlorinated zinc sulfate solution also contains one or more non-zinc metal ions that can form complexes with chloride ions. These non-zinc metal ions can form complexes with chloride ions, thereby improving chlorine extraction. The non-zinc metal ions can be selected from Fe... 3+ Cu 2+ Co 2+ Ni 2+ Mn 2+ One or more of the following. Preferably, the non-zinc metal ions are selected from Fe. 3+ and Cu 2+ .

[0045] In the chlorine-containing zinc sulfate solution, chlorine (Cl...) - ) and non-zinc metal ions (Me x+ molar ratio =(0.001 ~ 100):1, more preferably a molar ratio = (0.003 ~ 25):1. Here, Indicates the number of moles of chlorine. Describing non-zinc metal ions Me x+ The number of moles.

[0046] In step (1), the volume ratio of the chlorine-containing zinc sulfate solution to the organic phase can be (20:1) ~ (1:20), preferably (10:1) ~ (1:10). The number of extraction stages can be 1 to 20, preferably 1 to 5. In some embodiments, extraction can reduce the chlorine content in the zinc electrolyte to below 500 ppm, meeting the requirements for the use of the zinc electrolyte. In some embodiments, extraction can achieve a chlorine extraction rate greater than 93%, or can achieve a chlorine content in the chlorine-extracting tail liquid of less than 300 ppm.

[0047] In step (2), the stripping agent can be an alkaline solution or an EDTA solution. The alkaline solution is an aqueous solution of an alkali selected from sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, calcium hydroxide, etc. The concentration of hydroxide ions in the alkaline solution can be 0.0001 ~ 3 mol / L, preferably 0.2 ~ 2 mol / L. The EDTA solution is an aqueous solution of EDTA with a pH of 5 ~ 14, and the EDTA concentration can be 0.0001 ~ 0.3 mol / L, preferably 0.1 ~ 0.2 mol / L.

[0048] In step (2), the volume ratio of the chlorine-loaded organic phase to the stripping agent can be (10:1) to (1:10), preferably (5:1) to (1:5). The number of stripping stages can be 1 to 20, preferably 1 to 5. In some embodiments, the stripping rate of chlorine can be greater than 97.13% through stripping.

[0049] Chlorine-enriched back-extraction solutions can be further processed to recover valuable components. For example, when using an alkaline solution as the back-extraction agent, the back-extraction solution contains hydroxide precipitates of non-zinc metal ions. These hydroxide precipitates can be recovered by filtration, and can be used to adjust the pH and the ratio of chlorine to non-zinc metal ions in the initial zinc sulfate solution. The filtered chlorine-containing filtrate can be used to prepare alkaline solutions or to further recover chloride salts.

[0050] The chlorine-loaded organic phase is back-extracted to become a blank organic phase, which can be recycled back to the extraction step in step (1).

[0051] In some embodiments, the solvent extraction method for removing chlorine according to the present invention may further include a washing step, in which the chlorine-loaded organic phase is washed with water, the washing step being performed after step (1) and before step (2). Washing can remove the zinc sulfate solution entrained in the organic phase and also back-extract some chlorine, but the washing step is not mandatory.

[0052] In the washing step, the water refers to water that contains no or trace amounts of inorganic salts, such as distilled water, deionized water, tap water, or well water. The volume ratio of water to the chlorine-loaded organic phase can be (20:1) to (1:20), preferably (10:1) to (1:10). The number of washing stages can be 1 to 20, preferably 1 to 5.

[0053] The extraction and dechlorination method according to the present invention can be carried out using a separatory apparatus known in the art, preferably in a series of separatory funnels, a mixing and clarifying extraction tank or a centrifugal extractor, and more preferably in a mixing and clarifying extraction tank or a centrifugal extractor.

[0054] The extraction and dechlorination method according to the present invention can be carried out intermittently or continuously, preferably continuously.

[0055] The terms C1~C used in this invention 16 Alkyl refers to a straight-chain or branched alkyl group containing 1 to 16 carbon atoms, such as straight-chain or branched alkyl groups having 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16 carbon atoms. It includes, without limitation, methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, isobutyl, n-pentyl, neopentyl, isopentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, etc. (C1~C) 14 Alkyl, C1~C 12 Alkyl, C1~C 10 Alkyl, C1~C8 alkyl, C1~C6 alkyl, C1~C3 alkyl, C2~C 10 The meanings of alkyl, C2~C9 alkyl, and C2~C8 alkyl are deduced accordingly.

[0056] The terms C3~C used in this invention 10 Alicyclic alkyl groups refer to saturated cyclic alkyl groups containing 3 to 10 carbon atoms, including the number of carbon atoms in the substituents. These saturated cyclic alkyl groups can be monocyclic or bicyclic, and examples include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, and cyclodecyl. The substituents can be one or more substituents selected from C1-C4 alkyl groups. The meaning of C3-C6 alicyclic alkyl groups follows the same principle.

[0057] The terms C6~C used in this invention 10 Aryl refers to an aryl group containing 6 to 10 carbon atoms, including the number of carbon atoms in the substituents. Examples include phenyl and phenyl groups substituted with one or more substituents selected from C1 to C4 alkyl groups, such as phenyl, tolyl, xylyl, etc. The meanings of C6 to C8 aryl groups are similar.

[0058] The terms C4~C used in this invention10 Alkyl alcohols refer to straight-chain or branched alkyl alcohols containing 4 to 10 carbon atoms, such as straight-chain or branched alkyl alcohols having 4, 5, 6, 7, 8, 9 or 10 carbon atoms, and non-limitingly include n-butanol, tert-butanol, isobutanol, n-pentanol, neopentanol, isopentanol, hexanol, heptanol, octanol, nonanol, decanol, etc.

[0059] The terms C5~C used in this invention 16 Alkanes refer to straight-chain or branched alkanes containing 5 to 16 carbon atoms. Straight-chain or branched alkanes with 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16 carbon atoms include pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, etc.

[0060] The terms C5~C used in this invention 16 Alicyclic alkanes refer to saturated cyclic alkanes containing 5 to 16 carbon atoms, including the number of carbon atoms of the substituents. The saturated cyclic alkanes can be monocyclic or bicyclic, such as cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, decahydronaphthalene, etc. The substituents can be selected from one or more substituents of C1 to C4 alkyl groups.

[0061] The terms C6~C used in this invention 10 Aromatic hydrocarbons refer to aromatic hydrocarbons containing 6 to 10 carbon atoms, including the number of carbon atoms of the substituents, such as benzene and benzene substituted with one or more substituents selected from C1 to C4 alkyl groups, such as benzene, toluene, xylene, etc.

[0062] The term "about" as used in this application has a meaning known to those skilled in the art, indicating that the corresponding numerical value can vary within a certain range, but the extent of such variation is limited to not affecting the achievement of the purpose of this invention. For example, the range of variation can be within ±20%, ±15%, ±10%, or ±5%.

[0063] Unless otherwise stated, the numerical ranges listed in this invention include the endpoint values ​​and all point values ​​between the endpoint values ​​that increase or decrease in the smallest unit of the endpoint value, as well as all subranges composed of these point values.

[0064] Example

[0065] To further illustrate the present invention, specific embodiments are provided to help those skilled in the art understand and implement the invention; however, the invention is not limited to these embodiments.

[0066] Reagents and sources

[0067] The amino-containing neutral phosphine extractant was synthesized and characterized according to the same or similar methods described in CN201410765062.1 and CN201611012369.X, and the characterization data are shown in the table below:

[0068]

[0069] Aviation kerosene and tributyl phosphate (TBP) were purchased from Shanghai Laya Chemical Co., Ltd.; sulfonated kerosene was purchased from Luoyang Aoda Chemical Co., Ltd.; and methylheptanol was purchased from Shanghai Cytec Chemical Co., Ltd.

[0070] Cyanex 923 was purchased from Wuhan Lanabai Pharmaceutical Chemical Co., Ltd.

[0071] Analytical grade copper sulfate pentahydrate and sodium chloride were purchased from Xilong Scientific Co., Ltd., anhydrous zinc sulfate, anhydrous ferric sulfate, anhydrous cobalt sulfate and anhydrous ferric chloride were purchased from Adamas Reagents Ltd., and anhydrous zinc chloride was purchased from Greagent.

[0072] The zinc electrolyte comes from the sulfuric acid leaching solution of the company's zinc raw materials, and its main components are shown in the table below.

[0073] Zinc Electrolyte Composition Table

[0074]

[0075] The chloride ion concentration in the solution was determined by argentometric titration.

[0076] The chlorine extraction rate of an organic zinc sulfate solution containing chlorine is calculated as follows:

[0077]

[0078] E represents the chlorine extraction rate (%). c at The concentration of chlorine at the raffinate outlet (g / L) is given. c a0 The initial chlorine concentration (g / L) of the zinc sulfate solution containing chlorine.

[0079] The chlorine back-extraction rate of the back-extraction agent on the chlorine-loaded organic phase is calculated as follows:

[0080]

[0081] η is the chlorine back-extraction rate (%). c st V represents the concentration of chlorine in the back-extraction solution (g / L). st The volume of the back-extraction solution (L (Examples 1-3) or the flow rate (L / min (Examples 4-9)) is used. c a0 Same as above, Va The volume of the chlorine-containing zinc sulfate solution (L (Examples 1-3) or flow rate (L / min (Examples 4-9)).

[0082] Example 1

[0083] Organic phase: The organic phase was prepared by mixing 0.1 L of 2-ethylhexylaminomethylphosphonic acid di(2-ethylhexyl) ester, which was used as an amino-containing neutral phosphine extractant, with 0.15 L of sulfonated kerosene, which was used as a diluent.

[0084] Chlorine-containing zinc sulfate solution: A chlorine-containing zinc sulfate solution prepared using zinc sulfate, zinc chloride, sodium chloride, and pure water, wherein chlorine (Cl...) - The concentration was 10.84 g / L, zinc (Zn) 2+ The concentration was 8.51 g / L, and the molar ratio of chlorine to zinc was n. Cl- : n Zn2+ =2.33, pH is 4.73.

[0085] The stripping agent is a 2.0 mol / L NaOH aqueous solution.

[0086] In a 60 ml separatory funnel, press the organic phase (V) O ), chlorine-containing zinc sulfate solution (V a ) and back-extraction agent (V st The volume ratio (V) O :V a :V st The ratio of organic phase to chlorine-containing zinc sulfate solution was 10:20:20 (mL). The organic phase was subjected to four-stage cross-flow extraction to obtain the chlorine-loaded organic phase and the chlorine-removing tail liquid. Then, the chlorine-loaded organic phase was subjected to one-stage back-extraction with a back-extraction agent to obtain a blank organic phase (which can be recycled) and a chlorine-containing back-extraction solution.

[0087] The chlorine concentration in the chlorine extraction tailings was 6300 ppm, and the chlorine extraction rate of the organic phase relative to the chlorine-containing zinc sulfate solution was 41.88%. The back-extraction rate of the back-extraction agent for the chlorine-loaded organic phase was 99.25%.

[0088] Example 2

[0089] In addition to adding copper sulfate during the preparation of chlorinated zinc sulfate solution to make the copper chloride molar ratio n Cl- : n Cu2+ Except for pH 5 and a final pH of 4.98, the other operations are the same as in Example 1.

[0090] The chlorine concentration in the chlorine extraction tail liquid was 231 ppm. The chlorine extraction rate of the organic phase to the chlorine-containing zinc sulfate solution was 97.87%, and the chlorine back-extraction rate of the back-extraction agent to the chlorine-loaded organic phase was 99.67%. The resulting back-extraction liquid was filtered to obtain copper hydroxide and chlorine-enriched solution.

[0091] Example 3

[0092] Except that the stripping agent is a 0.1 mol / L EDTA + 0.5 mol / L NaOH aqueous solution (pH 13.63), the other operations are the same as in Example 2.

[0093] The chlorine concentration in the chlorine extraction tailings was 192 ppm, and the chlorine extraction efficiency of the organic phase relative to the chlorine-containing zinc sulfate solution was 98.23%. The back-extraction efficiency of the back-extraction agent for the chlorine-loaded organic phase was 97.13%.

[0094] Example 4

[0095] Organic phase: The organic phase was prepared by mixing 2 L of 1-(2-ethylhexylamino)-1-phenylmethylphosphonic acid di(2-ethylhexyl) ester, which was used as an amino-containing neutral phosphine extractant, with 8 L of sulfonated kerosene, which was used as a diluent.

[0096] Chlorine-containing zinc sulfate solution: Add ferric sulfate to zinc electrolyte A, and after preparation, the molar ratio of chlorine to ferric sulfate is n. Cl- :n Fe3+ = 3.42, pH is 2.98.

[0097] The stripping agent is a 1 mol / L sodium carbonate aqueous solution.

[0098] The organic phase (V) was controlled in a 250 ml mixing and clarifying extraction tank. O ), chlorine-containing zinc sulfate solution (V a ) and back-extraction agent (V st ) flow ratio (V O :V a :V st The ratio of organic phase to chlorine-containing zinc sulfate solution was 2:1:1 (mL / min). The organic phase was continuously extracted with chlorine-containing zinc sulfate solution in 5 stages to obtain chlorine-loaded organic phase and chlorine-removing tail liquid. Then, the chlorine-loaded organic phase was continuously back-extracted with back-extracting agent in 2 stages to obtain blank organic phase (which can be recycled) and chlorine-containing back-extracting solution.

[0099] The chlorine concentration in the chlorine extraction tailings was 118.5 ppm, and the chlorine extraction rate of the organic phase to the chlorine-containing zinc sulfate solution was 99.53%. The back-extraction agent achieved a chlorine back-extraction rate of 99.65% for the chlorine-loaded organic phase. The resulting back-extraction solution was filtered to obtain metal hydroxide and chlorine-rich solution.

[0100] Example 5

[0101] Organic phase: The organic phase was prepared by mixing 2 L of 1-(2-ethylhexylamino)-1-methylethylphosphonic acid di(2-ethylhexyl) ester as an amino-containing neutral phosphine extractant, 1 L of TBP as a phase modifier, and 7 L of aviation kerosene as a diluent.

[0102] Chlorine-containing zinc sulfate solution: Cobalt sulfate and zinc chloride are added to zinc electrolyte A. After preparation, chlorine (Cl...) - The concentration was 31.27 g / L, and the cobalt chloride molar ratio was n. Cl- : n Co2+ = 4.24, pH is 3.18.

[0103] The stripping agent is a 1.50 mol / L NaOH aqueous solution.

[0104] The organic phase (V) was controlled in a 250 ml mixing and clarifying extraction tank. O ), chlorine-containing zinc sulfate solution (V a ) and back-extraction agent (V st ) flow ratio (V O :V a :V st The ratio of organic phase to chlorine-containing zinc sulfate solution was 3:1:1 (mL / min). The organic phase was continuously extracted with chlorine-containing zinc sulfate solution in 8 stages to obtain chlorine-loaded organic phase and chlorine-removing tail liquid. Then, the chlorine-loaded organic phase was back-extracted with back-extracting agent in 1 stage to obtain blank organic phase (which can be recycled) and chlorine-containing back-extracting solution.

[0105] The chlorine concentration in the chlorine extraction tailings was 190.75 ppm, and the chlorine extraction rate of the organic phase relative to the chlorine-containing zinc sulfate solution was 99.39%. The back-extraction agent had a chlorine back-extraction rate of 99.71% on the chlorine-loaded organic phase. The resulting back-extraction solution was filtered to obtain metal hydroxide and chlorine-rich solution.

[0106] Example 6

[0107] Organic phase: The organic phase was prepared by mixing 3 L of 1-(2-ethylhexylamino)-1-ethylpropylphosphonic acid di(2-ethylhexyl) ester as an amino-containing neutral phosphine extractant, 1 L of TBP as a phase modifier, and 6 L of sulfonated kerosene as a diluent.

[0108] Chlorine-containing zinc sulfate solution: Copper sulfate and zinc chloride are added to zinc electrolyte A. After preparation, chlorine (Cl...) - The concentration was 45.10 g / L, and the molar ratio of copper chloride to chlorine was n. Cl- : n Cu2+ = 6.12, pH is 3.39.

[0109] The stripping agent is a saturated aqueous solution of Ca(OH)2.

[0110] The organic phase (V) was controlled in a 250 ml mixing and clarifying extraction tank. O ), chlorine-containing zinc sulfate solution (V a ) and back-extraction agent (V st ) flow ratio (V O :V a :V st The ratio of organic phase to chlorine-containing zinc sulfate solution was 4:1:20 (mL / min). The organic phase was continuously extracted with chlorine-containing zinc sulfate solution in 10 stages to obtain chlorine-loaded organic phase and chlorine-removing tail liquid. Then, the chlorine-loaded organic phase was continuously back-extracted with back-extracting agent in 2 stages to obtain blank organic phase (which can be recycled) and chlorine-containing back-extracting solution.

[0111] The chlorine concentration in the chlorine extraction tailings was 140.24 ppm, and the chlorine extraction rate of the organic phase relative to the chlorine-containing zinc sulfate solution was 99.69%. The back-extraction agent achieved a chlorine back-extraction rate of 99.67% for the chlorine-loaded organic phase. The resulting back-extraction solution was filtered to obtain metal hydroxide and chlorine-rich solution.

[0112] Example 7

[0113] Organic phase: The organic phase was prepared by mixing 3 L of 1-(N-dodecylamino)-1-methylethylphosphonate diethyl ester as an amino-containing neutral phosphine extractant, 1 L of Cyanex 923 as an auxiliary extractant, and 6 L of aviation kerosene as a diluent.

[0114] Chlorine-containing zinc sulfate solution: Add ferric sulfate and zinc chloride to zinc electrolyte A. After preparation, chlorine (Cl...) - The concentration was 53.64 g / L, and the chlorine-ferric molar ratio was n. Cl- : n Fe3+ = 6.87, pH is 3.06.

[0115] The stripping agent is a 2.50 mol / L KOH aqueous solution.

[0116] The organic phase (V) was controlled in a 250 ml mixing and clarifying extraction tank. O ), chlorine-containing zinc sulfate solution (V a ) and back-extraction agent (V st ) flow ratio (V O :V a :V st The ratio of organic phase to chlorine-containing zinc sulfate solution was 8:1:4 (mL / min). The organic phase was continuously extracted with chlorine-containing zinc sulfate solution in 13 stages to obtain chlorine-loaded organic phase and chlorine-removing tail liquid. Then, the chlorine-loaded organic phase was back-extracted with back-extracting agent in 1 stage to obtain blank organic phase (which can be recycled) and chlorine-containing back-extracting solution.

[0117] The chlorine concentration in the chlorine extraction tailings was 187.74 ppm, and the chlorine extraction rate of the organic phase to the chlorine-containing zinc sulfate solution was 99.65%. The back-extraction agent achieved a chlorine back-extraction rate of 99.82% for the chlorine-loaded organic phase. The resulting back-extraction solution was filtered to obtain metal hydroxide and chlorine-rich solution.

[0118] Example 8

[0119] Organic phase: The organic phase was prepared by mixing 1000 L of 2-ethylhexylaminomethylphosphonic acid di(2-ethylhexyl) ester, which was used as an amino-containing neutral phosphine extractant, with 1500 L of sulfonated kerosene, which was used as a diluent.

[0120] Chlorine-containing zinc sulfate solution: Zinc electrolyte B-1 is used, in which chlorine (Cl...) - The concentration was 25.52 g / L, and the chlorine-ferric molar ratio n Cl- : n Fe3+ = 18.22, pH is 4.95.

[0121] The stripping agent is a 2.0 mol / L NaOH aqueous solution.

[0122] Controlling the organic phase (V) in a CTL-350S centrifugal extractor O ), chlorine-containing zinc sulfate solution (V a ) and back-extraction agent (V st ) flow ratio (V O :V a :V st The pilot-scale test was conducted with an organic phase containing chlorine and a zinc sulfate solution containing chlorine. The organic phase and the chlorine-containing tail liquid were obtained by three-stage continuous extraction. Then, the organic phase containing chlorine was back-extracted with a back-extracting agent in one stage to obtain the chlorine-containing tail liquid, the circulating blank organic phase (which can be recycled), and the chlorine-containing back-extracting solution.

[0123] The chlorine concentration in the chlorine extraction tailings was 263 ppm, and the chlorine extraction rate of the organic phase to the chlorine-containing zinc sulfate solution was 98.97%. The back-extraction agent achieved a chlorine back-extraction rate of 99.80% for the chlorine-loaded organic phase. The resulting back-extraction solution was filtered to obtain metal hydroxide and chlorine-rich solution.

[0124] Example 9

[0125] Organic phase: The organic phase was prepared by mixing 1000 L of 2-ethylhexylaminomethylphosphonic acid di(2-ethylhexyl) ester, which was used as an amino-containing neutral phosphine extractant, with 1500 L of sulfonated kerosene, which was used as a diluent.

[0126] Chlorine-containing zinc sulfate solution: Zinc electrolyte B-2 is used, in which chlorine (Cl...) - The concentration was 4.28 g / L, and the molar ratio of copper chloride to chlorine was n.Cl- : n Cu2+ = 21.74, pH is 4.87.

[0127] The stripping agent is a 2.0 mol / L NaOH aqueous solution.

[0128] Controlling the organic phase (V) in a CTL-350S centrifugal extractor O ), chlorine-containing zinc sulfate solution (V a ) and back-extraction agent (V st ) flow ratio (V O :V a :V st The ratio of 750:1625:75 (L / h) was used for pilot-scale testing. The organic phase was continuously extracted with a zinc sulfate solution containing chlorine in three stages to obtain the chlorine-loaded organic phase and the chlorine extraction tail liquid. Then, the chlorine-loaded organic phase was back-extracted with a back-extracting agent in one stage to obtain the chlorine extraction tail liquid, the circulating blank organic phase (which can be recycled), and the chlorine-containing back-extraction liquid.

[0129] The chlorine concentration in the chlorine extraction tail liquid was 300 ppm. The chlorine extraction rate of the organic phase to the chlorine-containing zinc sulfate solution was 93.00%, and the chlorine back-extraction rate of the back-extraction agent to the chlorine-loaded organic phase was 99.77%. The resulting back-extraction liquid was filtered to obtain copper-enriched material and chlorine-enriched solution.

Claims

1. Use of an amino-containing neutral phosphine extractant of the formula I: ###0001### wherein, （I） 2. The use of claim 1, wherein, R1 and R2 are each independently selected from C1 to C2. 12 alkyl; R3and R4are each independently selected from the group consisting of hydrogen, Ci-C8alkyl, C3-C8cycloalkyl, C6-C10aryl, and heteroaryl; 10 Cycloalkyl and C6-C10aryl; 10 aryl; R5and R6are each independently selected from the group consisting of C1-C6alkyl and hydrogen, and at most one of R5and R6is hydrogen. 16 alkyl and hydrogen, and at most one of R5and R6is hydrogen. R3 and R4 are each independently selected from the group consisting of hydrogen, Ci-C6 alkyl, C3-C6 cycloalkyl, and C6-C8 aryl; and / or R1and R2are each independently selected from C2-C10alkyl; and / or 10 alkyl; and / or the total number of carbon atoms of R1, R2, R3, R4, R5, and R6 is from 10 to 48.

3. The use of claim 1 or 2, wherein, R1 and R2 are the same alkyl; and / or the total number of carbon atoms of R1 and R2 is an integer between 4 and 20; and / or R3 is selected from the group consisting of hydrogen, Ci-C6 alkyl, C3-C6 cycloalkyl, and C6-C8 aryl, and R4 is selected from the group consisting of Ci-C6 alkyl, C3-C6 cycloalkyl, C6-C8 aryl, and hydrogen; and / or the total number of carbon atoms of R3 and R4 is an integer between 0 and 12; and / or the total number of carbon atoms of R5 and R6 is an integer between 1 and 24; and / or R5 is selected from C1~C 10 Alkyl group and hydrogen, R6 is selected from C1~C 14 Alkyl, and / or the total number of carbon atoms of R1, R2, R3, R4, R5, and R6 is from 13 to 36.

4. The use of claim 1 or 2, wherein, R1 and R2 are the same C2-C9 alkyl; and / or the total number of carbon atoms of R1 and R2 is an integer between 4 and 18; and / or R3 is selected from the group consisting of Ci-C3 alkyl and hydrogen, and R4 is selected from the group consisting of Ci-C3 alkyl and phenyl; and / or the total number of carbon atoms of R3 and R4 is an integer between 0 and 7; and / or the total number of carbon atoms of R5 and R6 is an integer between 2 and 20; and / or R5 is selected from C1~C8 alkyl groups and hydrogen, and R6 is selected from C1~C8 alkyl groups and hydrogen. 12 Alkyl, and / or the total number of carbon atoms of R1, R2, R3, R4, R5, and R6 is from 15 to 34. the amino-containing neutral phosphine extractant of formula I is one or more selected from the group consisting of:

5. The use of claim 1 or 2, wherein, 1 -(2-ethylhexylamino)methylphosphonic acid di(2-ethylhexyl) ester; 1 -(2-ethylhexylamino)- 1 -phenylmethylphosphonic acid di(2-ethylhexyl) ester; 1 -(2-ethylhexylamino)- 1 -methylethylphosphonic acid di(2-ethylhexyl) ester; 1 -(2-ethylhexylamino)- 1 -methylpropylphosphonic acid di(2-ethylhexyl) ester; 1 -(2-ethylhexylamino)- 1 -ethylpropylphosphonic acid di(2-ethylhexyl) ester; 1 -(N-n-dodecylamino)- 1 -methylethylphosphonic acid diethyl ester; 1 -(2-ethylhexylamino) n-propylphosphonic acid di(2-ethylhexyl) ester; 1 -(N-n-butylamino)ethylphosphonic acid di(2-ethylhexyl) ester.

6. A method for extracting chlorine, comprising the step of contacting an amino-containing neutral phosphine extractant as described in any one of claims 1 to 5 with a zinc sulfate solution containing chlorine to extract chlorine from the zinc sulfate solution containing chlorine.

7. The method of claim 6, which is carried out using a solvent extraction method, comprising the steps of: the organic phase comprises the amino-containing neutral phosphine extractant, an optional auxiliary extractant, an optional phase modifier, and a diluent; (1) extraction: the zinc sulfate solution containing chlorine is mixed with an organic phase for extraction to obtain an organic phase loaded with chlorine and a chlorine extraction tail liquid; wherein, (2) stripping: stripping the chlorine-loaded organic phase with a stripping agent to obtain a chlorine-enriched stripping solution.

8. The method of claim 7, wherein, ​ The auxiliary extractant is selected from neutral phosphorus or phosphine extractant; acidic phosphorus or phosphine extractant; neutral phosphamide extractant; and mixed extractant mixed in any ratio of the above extractants; The phase modifier is one or more selected from the group consisting of C4-C 10 alkanols and tributyl phosphate; The diluent is selected from C5-C 16 alkanes; aviation kerosene; sulfonated kerosene, liquid paraffin; C5-C 16 cycloalkanes; C6-C 10 aromatics; The stripping agent is alkali liquor or EDTA solution, the alkali is selected from sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, calcium hydroxide; the EDTA solution is EDTA aqueous solution with pH of 5-14, and the concentration of EDTA is 0.0001-0.3 mol / L.

9. The method of claim 7, wherein, In the organic phase, the volume ratio of the amino-containing neutral phosphine extractant, the optional auxiliary extractant, the optional phase modifier and the diluent is amino-containing neutral phosphine extractant: auxiliary extractant: phase modifier: diluent = 1-80: 0-25: 0-25: 20-99; and / or The content of chlorine in the zinc sulfate solution containing chlorine is 100 ppm or more.

10. The method of claim 7, wherein, In the organic phase, the volume ratio of the amino-containing neutral phosphine extractant, the optional auxiliary extractant, the optional phase modifier and the diluent is amino-containing neutral phosphine extractant: auxiliary extractant: phase modifier: diluent = 10-75: 0-20: 0-20: 25-90; and / or The content of chlorine in the zinc sulfate solution containing chlorine is 300 ppm or more.

11. The method of claim 6 or 7, wherein, The zinc sulfate solution containing chlorine comprises one or more non-zinc metal ions that form a complex with chloride ions, the non-zinc metal ions being one or more selected from the group consisting of Fe 3+ , Cu 2+ , Co 2+ , Ni 2+ , Mn 2+ .

12. The method of claim 11, wherein, In the zinc sulfate solution containing chlorine, the molar ratio of chlorine to non-zinc metal ions = (0.001 ~ 100)︰1, wherein, represents the number of moles of chlorine, represents the number of moles of non-zinc metal ions.

13. The method of claim 7, wherein, In step (1), the volume ratio of the zinc sulfate solution containing chlorine to the organic phase is (20:1) to (1:20); and the extraction stage is 1-20 stages. In step (2), the volume ratio of the chlorine-loaded organic phase to the stripping agent is (10:1) to (1:10), and the stripping stage is 1-20 stages.

14. The method of claim 13, wherein, In step (1), the volume ratio of the zinc sulfate solution containing chlorine to the organic phase is (10:1) to (1:10); and / or the extraction stage is 1-5 stages; and / or In step (2), the volume ratio of the chlorine-loaded organic phase to the stripping agent is (5:1) to (1:5); and / or the stripping stage is 1-5 stages.

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