Study on Gold (Ⅰ) Solvent Extraction from Alkaline Cyanide Solution by TBP with Addition of Surfactant

The new solvent extraction system for gold() from alkaline cyanide solution by TBP with addition of surfactant in aqueous phase was studied. The effect of various factors, such as equilibrium pH, constitution of organic phase, molar ratio of CPBAu(CN)2-, extraction time, aqueous/organic phase ratio, different initial gold concentration, equilibrium temperature, different diluent, different types of extractants and surfactants etc., was inspected. The results show that gold() can be extracted quantitatively by controlling the quantity of surfactant (CPB); both the equilibrium pH and diluent hardly influence percent extraction. Gold() percent extraction reaches more than 98% under the optimal experimental conditions. 30% vol TBP diluted by sulphonating kerosene can load gold() to rather high levels. Loading capacity is in excess of 38 g/L. The extraction mechanism is discussed and the overall extraction reaction is deduced.

Selective extraction of gold(Ⅲ) from hydrochloric acid-chlorine gas leach solutions of copper anode slime by tri-butyl phosphate(TBP)

The oxidative leaching causes to dissolve various impurities such as Fe, Cu, Pd, Se in copper anode slime. Organicextractant tri-butyl phosphate (TBP) was used to purify leach solution. Several parameters, such as TBP, HCl and chloride inorganicsalt concentrations were chosen in order to determine efficient state for impurities separation. Standard solvent extraction tests forextraction and separation of Au, Pd, Pt, Fe, Cu and Se were conducted with equal volume of aqueous and organic phases in batchexperiments. The effect of hydrochloric acid, organic phase and metals initial concentration were examined at ambient temperature. Itwas found that 0.25 mol/L TBP in the presence of 2.5 mol/L hydrochloric acid can cause high extraction of gold. Meanwhile, in theseconditions the extraction of other impurities is negligible. After extraction, pregnant organic phase was scrubbed by distilled waterand some impurities were removed. Finally, gold was stripped by sodium thiosulfate solution. The stripping solution does not haveany impurities. By adding H2SO4 to stripping solution containing Na2S2O2, SO2 gas is released and Au3+ ions could be reduced.

Extraction of gold, palladium, and platinum from acidic media with cyclic sulfoxide derivative

The extraction of gold （Ⅲ）, palladium （Ⅱ）, and platinum （Ⅳ） from the acidic media with the cyclic sulfoxide derivative of α-dodecyl-tetrahydrothiophene 1-oxide （dtmso） was investigated. Gold （Ⅲ）, palladium （Ⅱ）, and platinum （Ⅳ） could be separated from the acidic media with suitable sulfoxide concentration and acidity. The extraction reaction of gold （Ⅲ）, palladium （Ⅱ） or platinum （Ⅳ） is exothermic when dtmso is used as an extracting reagent. The coordination number was studied by the slope method. The results indicate that, in high acidity, the dtmso coordination number for extracting gold （Ⅲ） or palladium （Ⅱ） is 3, and that for platinum （Ⅳ） is 2. UV and FT-IR spectra were used to analyze the structure of the complex. Gold （Ⅲ） is coordinated with the oxygen atom in S=O group in dtmso, and palladium （Ⅱ） or platinum （Ⅳ） is coordinated with the sulfur atom in S=O group in dtmso.

Studies on the Extraction of Gold (I) Cyanide by Quaternary Ammonium Salt Using ^(198)Au as Tracer

The solvent extraction of KAu(CN)2 from alkaline solution by quaternary ammonium salts (trialkyl-methylammonium chloride or cetyltrimethylammonium bromide) was investigated by means of 198Au radioactive tracer method. Various parameters, such as the gold (I) concentration in aqueous phase, the modifier, emulsification at the interface of two phases, and phase ratio used in the extraction of gold (I) were studied. The results demonstrate that almost all gold (I) in the aqueous phase was practically extracted into the organic phase. The water content in the organic phase decreased significantly with increase of gold (I) concentration using long chain alcohol as modifier, in contrast with the system with tributyl phosphate (TBP) as modifier. Emulsification at the interface of two phases decreases with an increase of modifier concentration in the organic phase or with the addition of a small amount of lysozyme into the aqueous phase. The method with 198Au tracer can be directly used to determine the Au(I) concentration both in aqueous and organic phases, which is especially suitable for the low concentration of Au(I).

Solvent extraction of rubidium from gold waste using conventional SX and new CFE methods

Solvent extraction（SX） of rubidium（Rb） from leaching filtrate of gold waste（GW） in Mouteh Processing Plant by 18-crown-6（18C6） was studied. High potential of new column flotoextraction（CFE） method in extraction of Rb from dilute solutions was also demonstrated. First, the factors affecting SX of Rb from a synthetic rubidium sulfate solution(containing 100 mg·L-1Rb) were identified.0.05 mol·L-118C6 in kerosene, 0.02 mol·L-1picric acid in aqueous phase, aqueous to organic（A/O） ratio of 1, p H7 and mixing time of 15 min are the optimum values for affective factors. The three-stage precipitation with sodium carbonate, p H adjustment with sulfuric acid and two-stage evaporation and crystallization were conducted to purify the leaching from impurities such as Fe, Al, Mn, Ca and especially competing cations of K and Na. Almost complete extraction of Rb and K from final filtrate containing 0.08 mol·L-1picric acid was performed using 0.2 mol·L-118C6 in kerosene. The Rb and K strippings of 99.12 % and 9.93 %, respectively, are obtained with 2 mol·L-1nitric acid with A/O ratio of 2. Finally, the performance comparison of the CFE and SX methods in similar conditionsshows increased extraction of K and Rb by 16 % and 5 %,respectively, using CFE method.

Equilibrium and mechanism studies of gold(Ⅰ)extraction from alkaline aurocyanide solution by using fluorine-free ionic liquids

Solvent extraction based on ionic liquids is generally considered to be an environmentally benign and effective technology for gold(Ⅰ)recovery.The aim of this work is to study gold(Ⅰ)extraction from aurocyanide solution using fluorine-free ionic liquids[A336][SCN],[A336][MTBA]and[A336][Mal].Various factors that affect gold(Ⅰ)extraction(including concentration of ionic liquids,equilibrium pH,concentration of the modifier tributyl phosphate(TBP),reaction time and initial concentration of gold in an aqueous solution)were studied and optimized.The results indicate that the three Aliquat336-based ionic liquids all exhibit excellent behaviors for gold(Ⅰ)extraction.More than 99.8%of gold(Ⅰ)can be extracted from the aqueous phase into the ionic liquid phase.The gold-loaded ionic liquids were characterized using infrared spectroscopy and mass spectrometry to study the extraction mechanism of gold(Ⅰ).The results revealed that extraction of gold(Ⅰ)into the ionic liquid phase was based on an exchange reaction between the anion Au(CN)2-in aqueous solution and the anion SCN-in ionic liquid[A336][SCN].The logarithmic relationship between distribution coefficient and TBP concentration indicates that two TBP molecules are involved in the formation of the extracted complex.The extracted complex was determined to be A336^(+)·Au(CN)_(2)^(-)·2 TBP.In addition,the gold(Ⅰ)-loaded ionic liquids can be efficiently stripped using NH4 SCN,2-methylthiobenzoic acid and methyl maltol.The results establish that Aliquat 336-based ionic liquids have potential application prospects in gold(Ⅰ)recovery from cyanide solutions.

Gold Determination by Electrothermal Atomic Absorption Spectrometry After Preconcentration Using Natural Deep Eutectic Solvent Based on Menthol and Camphor

A novel analytical procedure for the determination of gold by electrothermal atomic absorption spectrometry combined with selective liquid-liquid extraction by natural deep eutectic solvents(NADESs)is presented.The extraction ability of the NADESs prepared using menthol,thymol and camphor toward gold in hydrochloric acid solutions was studied.The extraction efficiency was improved by optimizing the parameters including the composition of the NADES s,the volume ratio of organic and aqueous phases,kinetics,and acidity of the solution.Quantitative determination of gold was carried out by electrothermal atomic absorption spectrometry directly in the NADES s phase dissolved in isopropyl alcohol.The extraction recovery of gold from 1 mol/L HCl with the NADESs based on menthol and camphor mixed in a molar ratio 1:1 was 99.7%at an enrichment factor of 100.The limits of detection and quantification of the proposed procedure were 1μg/L and 3.3μg/L,respectively,with a relative standard deviation of less than 5%.The developed procedure was applied for determination of gold in the certified reference material of ore,environmental and waste waters.

Solvent Extraction Developments in Southern Africa

The largest solvent-extraction plant in the world at the time, the Nchanga Copper Operation, was in Zambia. The first commercial process using solvent extraction for the refining of the platinum-group metals was in South Africa. More recently, the Southern African region has seen the implementation of solvent extraction for other base metals, precious metals, and specialty metals. These include the world firsts of primary production of zinc at Skorpion Zinc in Namibia and the large-scale refining of gold by Harmony Gold in South Africa. Several other flowsheets that use solvent-extraction technology are currently under commissioning, development, or feasibility study for implementation in this part of the world, including those for the recovery of copper, cobalt, nickel, tantalum, and niobium.

CTMAB萃取Au(CN)_2^-体系中盐析剂反常效应

研究了阳离子表面活性剂萃取剂惰性稀释剂Au(CN) -2 体系萃金过程中盐析效应的规律。结果表明盐析剂的加入反而降低了金的萃取率。这说明盐析剂的作用机制与萃合物在负载有机相中的存在状态及结构密切相关。盐析剂的加入降低了水相中水分子的活度 ,不利于生成有机相中以水分子为桥的CTMA+ ·H2 O·TBP缔合大阳离子萃合物。对传统的溶剂萃取盐析效应提出了一些新的观点。

N235协同萃取碱性氰化浸金溶液中的金(I)

由N235与路易斯碱三辛基氧膦（TOPO）组成协同萃取体系，对碱性氰化浸金贵液中金（Ⅰ）协同萃取和反萃进行了研究．研究了有机相中N235含量、水相平衡pH、相比等因素对金（Ⅰ）萃取率的影响，考察了反萃液中氢氧化钠液浓度对负载金有机相的反萃效果．结果表明，采用有机相为10％＋10％协萃剂TOPO＋80％煤油的协萃体系，对pH=9～10和初始金（I）质量浓度ρ0=10．87mg/L碱性氰化浸金贵液进行萃取时，经一级萃取后，萃取率可高达98％左右；同时，采用0．05～0．1mol／L的氢氧化钠溶液可对负载有机相进行反萃，反萃率达到91％以上．

烃基-苯并噻唑亚砜从硫脲介质中萃取金的性能研究

研究了正丁基-苯并噻唑亚砜(NBBSO)萃取酸性硫脲介质中Au(I)的性能。用2.3mol/LNBBSO从[Au(I)]=0.200mg/mL,[H+]=0.08mol/L的溶液中萃取金,一次萃取率高达95%。NBBSO萃取金速度较快,5min达到萃取平衡,负载有机相用12.5%Na2SO3溶液反萃,反萃率达99.2%。对不同结构的烃基-苯并噻唑亚砜萃取硫脲介质中金的性能进行研究,结果表明亚砜的萃取性能受亚砜配位基团的电子密度和取代基的空间效应影响。

石油亚砜在硫脲浸金液中萃取Au(Ⅰ)之机理

研究表明石油亚矾在硫脲浸金液中萃金属于中性络合溶剂化机理。萃合物的组成为Au[SC(NH_2)_2)_2^+·1/2SO_4^(2-)·3PSO。石油亚砜通过亚砜基上硫原子与金(Ⅰ)配位。

季铵盐萃取从碱性氰化液中综合提取金、银、铜的半工业试验

对用季铵盐苹取从氰化液中综合提取金、银、铜新工艺进行了小型工业试验,结果表明:金、银、铜的总收率大于99%,高流比立式混和澄清器的混和性能好,分层速度快且易于操作。本工艺具有能耗低、操作成本省及回收率高的特点,并便于大工业连续化生产。

二烷基亚砜—胺二元系从氰化物溶液中萃取金

研究了二烷基亚矾—胺从氰化物溶液中萃取金的反应中,亚矾和胺的化学结构以及萃取条件对萃金效果的影响。结果表明二烷基亚砜—仲胺体系在适当条件下可从较高pH(10～11)的氰化物溶液中有效地萃取金,并能与大多数共存金属元素达到很好的分离。此外,还具易于反萃的优点,是有应用前景的新型萃取体系。

碱性氰化液中加表面活性剂用TBP萃取金的研究

研究提出了在碱性氰化液中加入表面活性剂萃取金的新型萃取体系。考查了平衡pH值、有机相组成、CPB :Au(CN) 2 (摩尔 )、混相时间、相比、不同金初始浓度、温度、萃取剂类型及不同稀释剂、表面活性剂对萃取率的影响。控制表面活性剂用量 ,能使TBP选择性地定量萃取金 ;平衡pH值及稀释剂用量对萃取率影响不大 ;在优化实验条件下金的萃取率达 98%以上 ;用 30 %TBP +70 %磺化煤油的有机相 ,金的萃取容量达 380 4 2mg/L。讨论了萃取机理 ,推断了萃取反应式。

溶剂萃取从碱性氰化物溶液中回收金

概述近十年来溶剂萃取法从碱性氰化物溶液中回收金的研究工作。包括磷类萃取剂胺类萃取剂和胍类萃取剂的应用。

TBP与胺萃取碱性氰化物中的金

研究了TBP-胺二元萃取体系从碱性氰化液中萃取[Au(CN)2]-及反萃取的可能性,考察了不同类型的胺、平衡pH值、胺含量、TBP含量等对萃取率的影响。在优化实验条件下,用含40%TBP-10%胺(正辛胺)的磺化煤油有机萃取体系,对金的萃取率达到97%以上,对金的萃取容量达3.8g/L,但仍未达饱和。应用试验2级萃取率可达99%。

用磷酸三丁酯从多硫化物含金贵液中萃取金的研究

研究了磷酸三丁酯 (TBP)从多硫化物含金贵液中萃取金的规律 ,考察了一些影响萃取平衡的因素。实验结果表明 :TBP能在强碱性多硫化物介质中萃取金 ,萃取时水相和有机相条件的改变都对萃取有影响。水相Sx2 - 浓度的增加对萃取有利 ,当水相中有NH3·H2 O存在时 ,适宜的Sx2 - 浓度为 1.5mol L ;有机相中TBP浓度的增加 ,萃取率增加 ;温度及水相初始Au(Ⅰ )浓度的变化对萃取的影响不大 ;萃取适宜的稀释剂为烷烃类稀释剂 ;水相中NH3·H2 O的存在有无对萃取影响很大 。

EXAFS研究硫酸硫脲反萃季铵氰化金的机理

季铵盐可以直接从氰化浸出液中萃取金 ,但反萃困难。酸性硫脲通空气反萃体系是目前从季铵盐中反萃氰化金最有效的体系 ,但对其机理的研究很少。文章采用扩展X射线吸收精细结构 (EXAFS)等方法研究了硫酸硫脲从负载氰化金季铵盐中反萃金的机理。研究结果表明 ,在反萃过程中 ,硫酸、硫脲和硫脲金都能以中性分子进入有机相 ,中性缔合在季铵盐反萃过程中不可忽视。反萃机理如下 :(1)硫酸和硫脲首先进入有机相被萃取 ;(2 )在有机相中 ,硫脲争夺金的氰根配位 ,使氰化金变成硫脲金 ,同时游离出来的氰根与硫酸中的氢离子作用变成氢氰酸 ,在鼓空气搅拌条件下氢氰酸被空气迅速带走排除 ;(3)硫脲金配合物在有机相和水相中分配 ,大部分硫脲金进入水相 ,从而达到反萃的目的。

PSO-ⅢA(3)亚砜萃取金钯铂的差异及其解释

研究了盐酸介质中PSO-ⅢA(3)石油亚砜(自制)萃取Au、Pd、Pt的性能,提出萃取分离Au、Pd、Pt的可能性.探讨其萃取机理,并从机理的角度解释亚砜萃取Au、Pd、Pt能力上的差异.