阅读说明：本技术 2-乙基己基三丁基溴化膦从碱性氰化液中萃取铱的方法 (Method for extracting iridium from alkaline cyanide solution by using 2-ethylhexyl tributyl phosphine bromide ) 是由 黄章杰 陈慕涵 金次 邵敏 范梅 罗国婷 叶群 葛云松 陈明军 于 2019-11-29 设计创作，主要内容包括：2-乙基己基三丁基溴化膦从碱性氰化液中萃取铱的方法,涉及从碱性氰化液中提取铱的工艺。包括调节Ir(CN)<Sub>6</Sub><Sup>3-</Sup>料液pH9.0-11.0作为萃取体系的水相；以2-乙基己基三丁基溴化膦为萃取剂,以三辛基氧化膦或三烷基氧化膦或磷酸三丁酯或二异辛基亚砜之一为协萃剂,以氯仿或环己烷或磺化煤油之一为稀释剂,2-乙基己基三丁基溴化膦在有机相中的浓度为0.02~0.05 mol/L；混相、静置分层将Ir(CN)<Sub>6</Sub><Sup>3-</Sup>从水相转移到有机相,用0.2~0.6 mol/L NaBr溶液反萃铱等。本发明溶剂体系饱和萃取容量高,反萃容易,萃取周期短,反萃体系无需再生处理即能循环使用,4次循环后回收率大于96%,成本低,具有推广应用前景。(A method for extracting iridium from alkaline cyanide solution by using 2-ethylhexyl tributyl phosphonium bromide relates to a process for extracting iridium from alkaline cyanide solution. Including adjusting Ir (CN) 6 3‑ The pH value of the feed liquid is 9.0-11.0 and is used as the water phase of the extraction system; taking 2-ethylhexyl tributyl phosphine bromide as an extracting agent, taking trioctylphosphine oxide or trialkyl phosphine oxide or tributyl phosphate or diisooctyl sulfoxide as a co-extracting agent, taking chloroform or cyclohexane or sulfonated kerosene as a diluting agent, wherein the concentration of the 2-ethylhexyl tributyl phosphine bromide in an organic phase is 0.02-0.05 mol/L; mixing, standing and layering Ir (CN) 6 3‑ Transferring the water phase to an organic phase, and back extracting iridium and the like by using 0.2-0.6 mol/L NaBr solution. The solvent system of the invention has high saturated extraction capacity, easy back extraction and short extraction period, the back extraction system can be recycled without regeneration treatment, the recovery rate is more than 96 percent after 4 times of circulation, the cost is low, and the invention has popularization and application prospect.)

A process for extracting iridium from alkaline cyanide solution using 2-ethylhexyl tributyl phosphine bromide, comprising the steps of:

(1) will contain Ir (CN)₆ ^3-Adjusting the pH value of the feed liquid to be within 9.0-11.0 to be used as a water phase of an extraction system;

(2) preparing an organic phase consisting of an extracting agent, a diluent and a co-extracting agent, wherein 2-ethylhexyl tributyl phosphine bromide (ETPPB for short) is used as the extracting agent, and the concentration of the extracting agent in the organic phase is 0.02-0.05 mol/L;

the co-extractant is one of trioctylphosphine oxide (TOPO), trialkyl phosphine oxide (TRPO), tributyl phosphate (TBP) or diisooctyl sulfoxide (DIOSO), and the volume of the co-extractant accounts for 10-20% (V/V) of the volume of the organic phase;

the diluent is one of chloroform, cyclohexane or sulfonated kerosene, and the volume of the diluent is the balance of an extracting agent and a synergistic agent;

(3) adding the water phase and the organic phase into a separating funnel according to the ratio of the organic phase to the water phase (O/A) of 1: 1-1: 3 for mixing 2-5 minutes, standing for layering, and adding Ir (CN)₆ ^3-Transfer from the aqueous phase to the organic phase;

(4) taking the iridium-loaded organic phase extracted in the step (3), putting the organic phase into another separating funnel, adding NaBr solution with the concentration of 0.2-0.6 mol/L according to the ratio of the organic phase to the water phase (O/A) of 1: 1-3: 1, mixing for 1-6 minutes, standing for layering, and back extracting Ir (CN) in the organic phase₆ ^3-；

(5) Taking the above step (4) to back extract Ir (CN)₆ ^3-Washing the organic phase with water to remove excessive NaBr, returning to step (3), and extracting the same Ir (CN)₆ ^3-The feed liquid realizes the reutilization of the ETPPB extraction system.

2. The process of claim 1, wherein step (3) further comprises determining the concentration of Ir in the aqueous phase and calculating the extraction rate of ETPPB from Ir.

3. The method according to claim 1, wherein the step (4) is further performed by determining the concentration of Ir in the stripping phase and calculating the recovery rate of Ir.

Technical Field

The invention belongs to precious metal hydrometallurgy, and particularly relates to a process for extracting iridium from alkaline cyanide solution.

Background

Platinum group metals are extremely scarce metal resources in China, and platinum group metal iridium has wide application in the industries of chemical engineering, aerospace, communication and the like due to excellent thermoelectric transmission and high-temperature oxidation resistance. Two important channels for obtaining iridium are platinum group metal mining and iridium alloy secondary resource recovery. The pressure cyanidation leaching process is a valuable metal extraction technology which is widely adopted in hydrometallurgy, in recent years, along with the large-scale application of the process technology in platinum group metal metallurgy, a plurality of iridium-containing alkaline cyanidation leachate needs to be refined, but an effective refining method is not found at home and abroad aiming at the separation and extraction of iridium in an alkaline cyanidation liquid medium, and the application of the pressure cyanidation technology in platinum group metal hydrometallurgy is severely restricted. The research on a refining process including a solvent extraction method and the realization of large-scale solvent extraction and separation of iridium in an alkaline cyanide solution medium is a key technical problem which needs to be solved urgently by current platinum group metal hydrometallurgy. The alkyl quaternary phosphine ionic liquid has the advantages of difficult volatilization, stable property, good solubility and the like, and is widely used for extraction and separation of platinum group metal ions, the alkyl quaternary phosphine ionic liquid extraction system reported in the literature is mostly limited to an acidic medium, 2-ethylhexyl tributyl phosphonium bromide (ETPPB for short) used in the invention is a branched alkyl quaternary phosphine ionic liquid, and the extraction of iridium in an alkaline cyanide solution medium by taking the ETPPB as an extractant is not reported in the literature.

Disclosure of Invention

The invention aims to establish a method for extracting iridium from alkaline cyanide solution by using alkyl quaternary phosphine ionic liquid ETPPB, which has short extraction period and little pollution, is easy to back extract and can be recycled for multiple times without regeneration treatment.

The purpose of the invention is realized by the following technical scheme:

the method for extracting iridium from alkaline cyanide solution by using 2-ethylhexyl tributyl phosphine bromide comprises the following steps:

(1) will contain Ir (CN)₆ ^3-Adjusting the pH value of the feed liquid to be within 9.0-11.0 to be used as a water phase of an extraction system;

(2) preparing an organic phase consisting of an extracting agent, a diluent and a co-extracting agent, wherein 2-ethylhexyl tributyl phosphine bromide is used as the extracting agent, and the concentration of the extracting agent in the organic phase is 0.02-0.05 mol/L;

the synergist is one of trioctylphosphine oxide (TOPO) or trialkyl phosphine oxide (TRPO) or tributyl phosphate (TBP) or diisooctyl sulfoxide (DIOSO), and the volume of the synergist accounts for 10-20% (V/V) of the volume of the organic phase;

the diluent is one of chloroform, cyclohexane or sulfonated kerosene, and the volume of the diluent is the balance of an extracting agent and a synergistic agent;

(3) according to the ratio of the organic phase to the aqueous phase (O/A) of 1: 1-1: 3, putting the aqueous phase and the organic phase into a separating funnel, mixing the phases for 2-5 minutes, standing and layering, and adding Ir (CN)₆ ^3-Transfer from the aqueous phase to the organic phase;

(4) taking the iridium-loaded organic phase extracted in the step (3), putting the organic phase into another separating funnel, adding NaBr solution with the concentration of 0.2-0.6 mol/L according to the ratio of the organic phase to the water phase (O/A) of 1: 1-3: 1, mixing the phases for 1-6 minutes, standing and layering, and back extracting Ir (CN) in the organic phase₆ ^3-；

(5) Taking the above step (4) to back extract Ir (CN)₆ ^3-Washing the organic phase with water to remove excessive NaBr, returning to step (3), and extracting the same Ir (CN)₆ ^3-The feed liquid realizes the reutilization of the ETPPB extraction system.

The step (3) is further as follows: and (4) measuring the concentration of Ir in the aqueous phase, and calculating the extraction rate of the Ir extracted from the ETPPB.

The step (4) is further as follows: the concentration of Ir in the stripping phase was determined and the recovery of Ir was calculated.

The molecular formula of the 2-ethylhexyl tributyl phosphonium bromide (ETPPB for short) named in the technical scheme is C₂₀H₄₄BrP, relative molecular mass 395.22,¹H NMR(400MHz,CDCl₃) δ 2.52 to 2.45(m, 7H),1.60 to 1.53(m,22H),1.03 to 0.89(m,15H) ppm, the structural formula is:

the above substantive features and advances were based on extraction experiments and results, including:

1.pH value extraction of Ir (CN) from ETPPB₆ ^3-Effect of Performance

Fixing Ir (CN) in the liquid to be extracted at room temperature₆ ^3-The initial concentration of the extract is 141mg/L, the concentration of ETPPB in the organic phase is 0.04mol/L, the ratio of the organic phase to the aqueous phase (O/A) is 1:1, the mechanical oscillation is carried out for five minutes, namely the extraction time t is 5min, sulfonated kerosene is selected as a diluent of an extraction system, TOPO is selected as a co-extraction agent, and 20 percent of TOPO (V) is contained in the organic phase_TOPO/V_{Organic phase}) The total volume of the organic phase is 20mL, and different pH values extract Ir (CN) from ETPPB₆ ^3-The effect of the properties is shown in table 1.

TABLE 1 pH value versus ETPPB extraction Ir (CN)₆ ^3-Effect of Performance

2. And (3) determining the saturated extraction capacity of ETPPB:

controlling the pH value of the solution to be 10 at room temperature, comparing the organic phase with the water phase (O/A) by 1:1, extracting for 5 minutes, and fixing Ir (CN) in the solution to be extracted₆ ^3-The initial concentration of the extraction system is 132mg/L, sulfonated kerosene is selected as a diluent of the extraction system, TOPO is selected as a co-extractant, and the organic phase contains 20 percent of TOPO (V)_TOPO/V_{Organic phase}) The total volume of the organic phase is 50mL, and the continuous extraction method is adopted to determine the extraction Ir (CN) of ETPPB solution with different concentrations₆ ^3-The extraction capacity was saturated.Extraction of Ir (CN) from ETPPB solutions of different concentrations₆ ^3-The saturated extraction capacity is shown in table 2:

TABLE 2 ETPPB solutions of different concentrations for extraction of Ir (CN)₆ ^3-Saturated extraction capacity

The experimental results of tables 1 and 2 show that: the ETPPB can quantitatively extract iridium from alkaline cyanide solution, the extraction pH range is wide (table 1), the saturated extraction capacity is high (table 2), the pH value is in the range of 9.0-11.0, and the extraction effect is optimal.

The invention has the following substantive characteristics and progresses:

1. the back extraction is easy, and the back extraction system can perform the recycling extraction again without regeneration treatment;

2. the extraction system has stable performance, the recovery rate is more than 96 percent after 4 times of circulation, the cost is low, and the method has large-scale application prospect

3. The extraction and back extraction reaction has high dynamic speed, can reach balance within minutes, has short extraction period and low cost;

the invention will be further described below by means of specific embodiments for a better understanding of the invention, without limiting the scope of protection of the invention by the examples cited.

Detailed Description