三辛胺萃取草酸的机理

选择草酸稀溶液为萃取对象 ,采用三辛胺 (TOA)为络合剂 ,正辛醇为稀释剂 ,开展了TOA萃取草酸的机理研究 .以红外谱图为分析手段 ,通过测定络合剂及被萃溶质的浓度对萃合物组成的影响 ,得到其萃合物以 1∶1和 1∶2 (酸 :碱 )两种形式存在于有机相中 ;并通过萃取平衡实验 ,获得了TOA萃取草酸的平衡特性 ,进一步验证了萃合物组成 .以此为基础建立了草酸与TOA两种萃合比情况下的数学模型 ,拟合求得了K₁₁及K₁₂ ,其中 1∶2萃合物的化学萃取平衡常数远远小于 1∶1的相应值     

用硫脲从季铵盐萃取液中反萃金,银,铜的探索

本文叙述了硫脲和季镀盐的基本物化性质,分析并论证了硫脲盐酸漓液反萃取季铵盐负载有机相中金、银、铜的可能性及其机理。理论分析和实验结果均表明,在酸性条件下,硫脲具有取代季铵盐萃取金、银、铜的萃合物中CN~-配位体的能力。CN~-配位体被中性硫脲SC(NH_2)_2取代后,使原来带负电的络阴离子M(CN)_2~-变成带正电的络阳离子M(SC(NH_2)_2)_2~+,带相同电荷的两离子(R_3CH_3N)和M(SC(NH_2)_2)_2~+互相排斥,迫使萃合物解离并分别进入有机相和水相,由此达到比较完全的反萃目的。反萃后的金、银、铜硫脲络合物和对应氰离子络合物比较其稳定常数大为降低,故易于被还原成金属元素。同时,通过控制反萃液的酸度,可将金与银、铜大致分离。     

草酸强化三价铁离子的反萃性能

二(2-乙基己基)磷酸(P204)常作为溶液净化除铁的萃取剂，P204-磺化煤油体系中Fe³⁺与有机相形成络合能力较强的萃合物，使得Fe³⁺反萃比较困难，需采用较高浓度的酸作为反萃剂，但高浓度的酸会破坏有机分子的结构，影响萃取剂循环利用。针对P204-磺化煤油负铁有机相反萃困难的问题，提出利用草酸为反萃剂对负载1g/L铁的P204-磺化煤油有机相的反萃行为进行研究，考察了反萃转速、草酸浓度、反萃温度、反萃时间和相比对Fe³⁺反萃率的影响。结果表明：以反萃转速200r/min，草酸0.4mol/L，反萃时间10min，反萃温度40℃，反萃相比1∶1，采用二级逆流萃取方式，铁的反萃率可以达到99%以上；Fe³⁺反萃过程是吸热反应，其反应的焓变为81.58kJ/mol，反萃过程符合准一级反应动力学方程，对应活化能为49.5kJ/mol。进一步研究了反萃后P204-磺化煤油有机相对Fe³⁺的萃取性能。结果表明：经5次草酸反萃后的P204-磺化煤油有机相萃铁性能几乎不变，对比于高浓度的酸反萃，草酸反萃简化了反萃流程，降低了萃取剂的消耗。     

2-乙基己基膦酸单(2-乙基己基)酯(HEHEHP)溶剂萃取氯化镓的机理

本文研究了用2-乙基己基膦酸单(2-乙基己基)酯(HEHEHP)从盐酸介质中对氯化镓萃取的机理。观察了萃取时间、萃取剂的浓度、水相中的酸度及镓离子的浓度对萃取分配比的影响。寻找合适的反萃液。在pH1.9～2.4范围内,Ga(Ⅲ)萃取的分配比与有机相中[HEHEHP]_2浓度的平方成线性关关系,反比于水相中氢离子浓度的平方,形成萃合物GaCl(HA_2)_2,萃取反应的表观平衡常数K=0.280(15℃.μ=0.025)。     

1－苯基－3－甲基－4－（α－呋喃甲酰基）－5－吡唑酮对稀土（Ⅲ）钍（Ⅳ）和铀（Ⅳ）的萃取行为研究

研究了题示试剂（ＨＡ）萃取稀土（Ⅲ）、钍（Ⅳ）和铀（Ⅵ）的行为，研究了萃取机理，确定了萃合物的组成，求得了萃取平衡常数，并制备了稀土的固态萃合物，对其组成、ＩＲ、ＵＶ、ＴＧ和ＤＴＡ进行了表征。     

DTMSO的合成及其萃金性能研究

研究了环状亚砜衍生物 α-十二烷 -四氢噻吩亚砜 ( DTMSO)的合成及其萃金性能 ,用 0 .1 mol/ L DTMSO从金浓度为 0 .89g/ L的 0 .1 mol/ L HCl的溶液中萃金 ,一次萃取率 >98% ;DTMSO在低酸度盐酸溶液中 ,以中性配合溶剂化机理萃金 ,萃合物组成为 ( HAu Cl4)· 3DTMSO,DTMSO通过氧与金配位 ;高酸度下 ,以离子缔合机理萃金 ,萃合物组成为 ( H· n H2 O· 3DTMSO) + Au Cl- 4 ,萃合物发生内配位转变     

1—苯基—3—甲基—4—（α—呋喃甲酰基）—5—吡唑酮对稀土（Ⅲ）钍（Ⅳ）和铀（Ⅳ）...

研究了题示试剂（ＨＡ）萃取稀土（Ⅲ）、钍（Ⅳ）和铀（Ⅳ）的行为，研究了萃取机理，确定了萃合物的组成，求得了萃取平衡常数，并制备了稀土的固态萃合物，对其组成、ＩＲ、ＵＶ、ＴＧ和ＤＴＡ进行了表征。     

肟类萃取洁霉素的研究

本文首次将肟类萃取剂用于洁霉素的萃取，研究了其萃取规律.在中性及弱碱性条件下，所选用的氧肟－84、酮肟－85及N510三种肟类均可有效地萃取洁霉素，且在酸性条件下容易反萃.无论氧肟还是酮肟均按溶剂化历程萃取洁霉素，前者形成L.S型萃合物，后者形成L.2S型萃取合物（L－洁霉素，S－肟类萃取剂）.     

二(2—乙基已基)磷酸萃取钆的研究

本文研究了采用二(2—乙基己基)磷酸(D_2EHPA)从盐酸体系中萃取钆的机理,确定了萃合物的组成为GdA_3·3HA,测定出萃取平衡常数K_e=10~(0·54)(20±0.5℃)。实验表明当起始水相酸度为0.1213M时,萃取率可高达99.89％将采用4M盐酸进行反萃,反萃率达99.96％。     

十八烷基二甲基苄基氯化铵从碱性氰化液中固相萃取金的研究

基于十八烷基二甲基苄基氯化铵(BDMSAC)与Au(CN)-2络阴离子生成的离子缔合物可被C18反相键合硅胶固相萃取柱萃取、富集,建立了一种从碱性氰化液中高富集倍数固相萃取金的方法。该方法用于从碱性氰化液中固相萃取痕量金,萃取回收率可超过98%,同时研究了C18反向固相萃取金的机理,也创造性地提出了一种从碱性氰化液中提取金的新工艺。     

Separation of vanadium and tungsten in roasting-acid leaching solutions of the spent selective catalytic reducing denitration catalyst by co-extraction using hydroxyoxime extractant-quaternary ammonium salt extractant LIX984–N263 extractant

This study presents a synergistic extraction and recovery of vanadium and tungsten by mixed extractants (LIX984 and N263) from an acid leaching solution which was obtained from spent denitrification catalysts by chlorination heat treatment and acid leaching. Through thrice counter-flow extraction, 99.5% V and 99.7% W were extracted, while 3.0% Fe, 2.9% Ti, 2.1% P, and 3.3% Mg were co-extracted at a LIX984:N263 volume content of 22.0%, the phase ratio of 2.5 and the mother liquor's pH of 2.5. Then, at 0.80 mol/l NaOH and a phase ratio of 1, 99.9% tungsten and 99.1% vanadium were stripped from the organic phase to the aqueous phase. Subsequently, the aqueous phase's tungsten of 99.3% and vanadium of 98.1% were separated as calcium tungstate and ammonium metavanadate, respectively. In contrast, the residual solutions containing tungsten and vanadium can be returned to the following purification separation process to recover the valuable metals from the solution. Roasting converts the precipitated calcium tungstate and ammonium metavanadate to V₂O₅ and WO₃ products. In addition, the thermodynamic analysis found the separation and recovery of tungsten and vanadium from the acid leach solution with LIX984:N263 to be an exothermic process. This method can be effectively extended for the separation of vanadium and tungsten from spent denitrification catalysts by the proposed process and validates the conclusion that metals with similar properties can be extracted using a mixture of extractants.     

EXTRACTION OF NIOBIUM AND TANTALUM WITH BIS-2-ETHYLHEXYL ACETAMIDE

ABSTRACT The extraction of Nb and Ta from acid solutions with bis-2-ethylhexyl acetamide and the stripping of these metals with sulphuric acid solutions were investigated. The organic phase was a binary solution of bis-2-ethylhexyl acetamide and xylene, while the aqueous phase was composed of hydrofluoric acid solution or hydrofluoric-sulphuric acid solution containing 3.5-13 Kg/m³ Nb and 5-10 Kg/m³ Ta. Sulphuric acid, hydrofluoric acid and nitric acid were used as salting out agents to understand the effect on the extraction.

Niobium and tantalum were not sufficiently extracted from hydrofluoric acid solutions, whereas the extraction of both metals remarkably increased with an addition of sulphuric acid to the aqueous phase. Both metals were completely co-extracted under the aqueous condition of 6N hydrofluoric acid and 8N sulphuric acid. The stripping occurred for both metals with high efficiency when water or dilute sulphuric acid was used as a stripping agent. The increase in sulphuric acid concentrations caused less stripping of Ta, while the stripping of Nb was maintained at 80% up to 7N sulphuric acid.     

Ion Exchange Resins for Gold Cyanide Extraction Containing a Piperazine Functionality, 2. Study of the Gold Extraction Reaction

Ion exchange technology is offered as an alternative to activated carbon for gold cyanide recovery. A new type of ion‐exchange resin (PS‐PIP) incorporating a piperazine group, linked to a styrene‐divinylbenzene macroporous network, is described. The extraction of Au(CN)₂^– and other metal cyanides with the PS‐PIP resin involves three modes of metal extraction: the protonated secondary amine groups of the resin (at acidic pH conditions), the free amine groups of the resin (at neutral and basic pH values) and the small portion of the quaternary ammonium groups participate in the gold extraction mechanism. The gold cyanide extraction reaction on the polymeric piperazine was studied by a combination of metal extraction data, from batch experiments, and IR and XPS spectroscopic analysis of the metal loaded polymers. Extraction isotherms of gold cyanide show that gold binding is possible from 40–60 mg Au/g of resin in alkaline solutions, up to 150 mg Au/g of resin in acidic solutions. Efficient stripping of gold from the resin was achieved using ethanol/water solutions of sodium hydroxide, or 0.5 mol/l thiourea in sulfuric acid solutions.     

Extraction of gold from cyanide or chloride media by Cyanex 923

A new phosphine oxide extractant, commercially known as Cyanex 923, has been studied in order to be applied in the recovery of gold from either cyanide or chloride aqueous media. Au(CN)₂⁻ is extracted by this reagent throughout the whole pH range. The presence of lithium salts in the media improves the extraction. The extraction mechanism proposed can be explained in terms of a solvating reaction, the species formed in the organic phase being the following: Li⁺Au(CN)₂⁻3(R₃PO). The stripping can be performed by low ionic strength solutions such as dilute KCN solutions, and the reaction is enhanced by an increase in temperature. In chloride media, the extractant is able to extract gold (III) in the entire range of acid concentrations. The amount of extraction agent required, to achieve the same level of extraction, in this medium is much lower than in the cyanide media. The temperature has a negative effect on the extraction. Another difference observed between the two media, is that the presence of ionic salts in chloride media has no influence on the extraction, which may be attributed to the fact that the extracted species, HAuCl₄, is a protonated instead of an ionic species. © 1998 SCI     

ANAEROBIC EXTRACTION OF COBALT IN A PULSE COLUMN

The effects of excluding air (oxygen) from a cobalt solvent extraction circuit were studied for LIX 64N extractant. After solvent extraction of divalent cobalt from ammoniacal solutions with chelating extractants such as LIX 64N, the loaded Co-chelate is believed to oxidize to a stable trivalent complex which resists subsequent stripping with mineral acids. To Improve stripping efficiency, cobalt was extracted and stripped in the absence of oxygen in pulsed, perforated-plate columns that were designed and constructed by the Bureau of Mines. When the ammoniacal cobalt(II) sulfate and LIX 64N solutions were purged, blanketed, and pulsed with argon, cobalt extraction exceeded 99%, and stripping with 1 vol % H₂SO₂ reached 98.5%. The stripped extractant was recycled to the extraction column with no loss of extraction efficiency in six passes through the circuit.     

Continuous Laboratory Gold Solvent Extraction from Cyanide Solutions using LIX 79 Reagent

Continuous laboratory solvent extraction of gold from cyanide solutions has been investigated by using LIX 79 guanidine‐based extractant. Different variables that affected the extraction included aqueous pH, extractant concentration and modifier concentration. Extraction isotherms of the aurocyanide complex with respect to the other cyanoanions were compared, and the following order of selectivity was observed: Au > Ag > Cu > Zn > Fe. According to the pH isotherms, aurocyanide can be extracted in alkaline media, and a better separation with respect to other cyano anions was obtained in the pH range 10.5–11.2. From the McCabe‐Thiele diagrams, better recovery was observed when using LIX 79 and tridecanol at 10 vol.‐%. Stripping gold from the loaded organic was carried out at pH > 12 by using NaOH and NaCN solutions. The pilot plant tests indicate that a two‐stage extraction followed by one strip step are more than adequate to obtain an overall process efficiency of 92 %. However, for those cases where copper is present significantly, a copper wash stage is recommended before gold stripping. In this case, stripping of copper is accomplished at a pH 10.8, whereas the gold stripping was done at a pH of 12.0.     

粉煤灰酸浸溶液中铁铝离子的萃取分离

采用N503和TBP、正辛醇、煤油组成的复合萃取体系,对粉煤灰酸浸溶液中的铝与铁进行萃取分离,考察盐酸浓度、氯离子浓度、萃取剂比例对Fe3+萃取率的影响,以低浓度HCl溶液反萃负载铁有机相,并通过逆流实验确定最佳工艺条件. 结果表明,采用N503:TBP:正辛醇:煤油=3:1:1:5(j)的萃取体系,在初始铁浓度为0.96 mol/L、铝浓度为0.22 mol/L、萃取相比O/A=2:1条件下,经5级逆流萃取,Fe3+的萃取率大于99.8%,铝几乎没有损失. 用0.01 mol/L HCl溶液作反萃剂,反萃相比O/A=2.5:1,经6级逆流反萃,反萃液中铁浓度达1.8 mol/L. 分析了有机相负载铁前后官能团的红外光谱图.     

Au(III) extraction using ketone compounds with physical properties superior to current commercial extractants

Dibutyl carbitol (DBC) and methyl isobutyl ketone (MIBK) are commercially available for the extraction of Au(III) from acidic chloride media through ion solvation. These extractants show high Au(III) extractability, but their physical properties have drawbacks in extraction processes. In this study, Au(III) extraction using a series of aliphatic ketone compounds was studied to find a novel extractant with advantageous properties compared with conventional extractants. These ketone compounds showed desirable Au(III) extractability, with those bearing shorter aliphatic chains showing higher extractability. Furthermore, their Au(III) extraction capacities exceeded industrial requirements. These compounds also had improved properties for metal processing compared with commercial extractants, namely, lower solubility in water, lower viscosity, and high flash points. A representative extractant, 2-nonanone, selectively extracted Au(III) over various metal ions. Gold extracted with 2-nonanone was recovered quantitatively as metallic gold by reduction using oxalic acid.     

Synergistic Extraction of U(VI), Th(IV), and Lanthanides(III) from Nitric Acid Solutions Using Mixtures of TODGA and Dinonylnaphthalene Sulfonic Acid

The extraction of U(VI), Th(IV), and lanthanides(III) from aqueous nitric acid solutions with mixtures of N,N,N′,N′-tetra(n-octyl)diglycolamide (TODGA) and dinonylnaphtalene sulfonic acid (HDNNS) in n-decane has been investigated. The extraction efficiency of U(VI), Th(IV), and Ln(III) ions is greatly enhanced by addition of HDNNS to an organic phase containing TODGA. The synergistic effect arises from the higher hydrophobicity of U(VI), Th(IV), and Ln(III) extracted species formed by TODGA and DNNS^? anions as compared to those formed by TODGA and NO₃^? ions as counter anions. The synergistic effect for U(VI), Th(IV), and Ln(III) extraction from aqueous nitric acid solutions with mixtures of TODGA and HDNNS becomes weaker when the acidity of the aqueous phase increases. A high synergistic enhancement is accompanied with a high selectivity of Ln(III) extraction from nitric acid solutions.