Recovery of indium from indium tin oxide by solvent extraction
Abstract and Figures
Recovery of indium from LCD screen wastes, which contain indium in the form of indium tin oxide (ITO) as the electrode material, is becoming economically and environmentally justified. Indium is a valuable metal and the present work was aimed to recover indium from ITO as the starting material to study the recovery of indium from waste LCD screens by solvent extraction.The apparent rate of dissolution in acidic media is slow requiring six hours for complete dissolution of the ITO sample in 1 M of either H2SO4 or HCl. Complete dissolution in HNO3 took significantly longer. The acid concentration was found to have a major effect on both the amount and rate of leaching allowing some leaching selectivity.Three solvent systems were chosen to study their selectivity for the separation of indium from tin: TBP, D2EHPA and a mixture of both. With either 1 M of TBP or 0.2 M of D2EHPA + 0.8 M of TBP, tin could be selectively extracted from a 1.5 M HCl solution of this metal. D2EHPA extracts both indium and tin from H2SO4 media but indium could be selectively stripped with HCl from the loaded D2EHPA. Based on these results, a scheme for separating and concentrating indium from ITO by solvent extraction is proposed. The scheme includes dissolving ITO into 1 M of H2SO4, then extracting indium and tin to D2EHPA followed by selective stripping of indium into 1.5 M of HCl. With this process, HCl solution containing 12.2 g/L of indium could be achieved.
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... Indium tin oxide (ITO) is a mixed oxide, usually consisting of 90-95 wt% indium oxide (In 2 O 3 ) and 5-10 wt% tin oxide (SnO 2 ). It is used as a light-transparent conductive coating, mainly in liquid crystal displays (LCDs) [9], but it is also found in PV technologies [8]. Its main compositional element, In, was considered a critical raw material by the EU in 2017. ...
... In lab scale, research is mainly conducted today on the recycling of In from ITO found in LCD screens by the use of hydrometallurgical methods. Leaching of the ITO material with inorganic and organic acids has been investigated in these cases [9,11,13]. Some of these studies investigated further the recovery of the leached In by solvent extraction and stripping [9,13], cementation [14] or precipitation [15]. ...
... Leaching of the ITO material with inorganic and organic acids has been investigated in these cases [9,11,13]. Some of these studies investigated further the recovery of the leached In by solvent extraction and stripping [9,13], cementation [14] or precipitation [15]. Ultrasonic leaching of ITO from LCD screens has also been tested, aiming to increase the leaching efficiency of In due to the cavitation effect [16,17]. ...
... Это связано с тем, что устойчивый октаэдрический анион InCl4в водном растворе прочно связан с двумя молекулами воды и сильно гидратирован, что затрудняет его экстракцию, тогда как аналогичный тетраэдрический комплекс [GaCl4]гидратирован слабо и хорошо экстрагируется, несмотря на то, что он на несколько порядков менее устойчив. Те же закономерности наблюдаются при экстракции нейтральных комплексов индия и галлия [InCl3(H2O)3] 0 и [GaCl3(H2O)] 0 [25,[27][28][29][30]. Важно отметить, что при экстракции растворами ТБФ сопутствующее индию олово может быть полностью селективно извлечено из 1,5 моль/л HCl раствором 1 моль/л ТБФ или смесью 0,2 моль/л Д2ЭГФК + 0,8 моль/л ТБФ [31]. Ввод в технологическую схему производственного процесса больших количеств соляной кислоты или хлоридов для повышения извлечения индия и галлия в данном случае крайне нежелателен, так как это осложняет дальнейшее выделение металлов из растворов электрохимическими методами. ...
... Известны статьи и патенты по экстракции индия (и галлия) смесями Д2ЭГФК с ТБФ [31], высшими алифатическими спиртами, алкиламинами [23], триалкилфосфиноксидами [39], октановой кислотой, изододецилфосфетановой кислотой (ИДДФК), диоктилфенилфосфорной кислотой (ДИОФФК) [40,41], которые являются антагонистами, то есть они ухудшают экстракцию этих металлов растворами Д2ЭГФК. Введение в экстрагент на основе Д2ЭГФК этих реагентов позволяет более полно и селективно проводить реэкстракцию индия и галлия в намного более мягких условиях. ...
Рассмотрена текущая ситуация с производством галлия и индия в России. Показано, что одним из перспективных сырьевых источников этих металлов являются полупродукты цинкового производства. Проведен анализ известных методов переработки отходов и полупродуктов цинкового производства для попутного излечения галлия при производстве индия. Ключевые слова: галлий, индий, цинковое производство, вельц-оксиды, сфалерит, комплексная переработка сырья, жидкостная экстракция.
Advanced high-tech applications for communication, renewable energy, and display, heavily rely on technology critical elements (TCEs) such as indium, gallium, and germanium. Ensuring their sustainable supply is a pressing concern due to their high economic value and supply risks in the European Union. Recovering these elements from end-of-life (EoL) products (electronic waste: e-waste) offers a potential solution to address TCEs shortages. The review highlights recent advances in pre-treatment and hydrometallurgical and biohydrometallurgical methods for indium, gallium, and germanium recovery from EoL products, including spent liquid crystal displays (LCDs), light emitting diodes (LEDs), photovoltaics (PVs), and optical fibers (OFs). Leaching methods, including strong mineral and organic acids, and bioleaching, achieve over 95% indium recovery from spent LCDs. Recovery methods emphasize solvent extraction, chemical precipitation, and cementation. However, challenges persist in separating indium from other non-target elements like Al, Fe, Zn, and Sn. Promising purification involves solid-phase extraction, electrochemical separation, and supercritical fluid extraction. Gallium recovery from spent GaN and GaAs LEDs achieves 99% yield via leaching with HCl after annealing and HNO 3 , respectively. Sustainable gallium purification techniques include solvent extraction, ionic liquid extraction, and nanofiltration. Indium and gallium recovery from spent CIGS PVs achieves over 90% extraction yields via H 2 SO 4 with citric acid-H 2 O 2 and alkali. Although bioleaching is slower than chemical leaching (several days versus several hours), indirect bioleaching shows potential, achieving 70% gallium extraction yield. Solvent extraction and electrolysis exhibit promise for pure gallium recovery. HF or alkali roasting leaches germanium with a high yield of 98% from spent OFs. Solvent extraction achieves over 90% germanium recovery with minimal silicon co-extraction. Solid-phase extraction offers selective germanium recovery. Advancements in optimizing and implementing these e-waste recovery protocols will enhance the circularity of these TCEs.
This paper represents a brief review of the activities and the results obtained so far within the Smelters research center aiming to recover indium from indium bearing residues including copper dross and run off zinc.
The experimental work was carried out in three main fields: leaching, solvent extraction and metallic indium precipitation.
A solution of di-2-ethylhexyl phosphoric acid (D2EHPA) in kerosene was found to be most convenient for purification and concentration of indium bearing solutions. Further purification of the strip liquor was carried out by an additional solvent extraction using TBP. Loaded TBP was stripped with water.
After the more electropositive impurities have been cemented on an indium plate, indium is cemented by means of an Al-Zn alloy. Thus, a relatively high purity indium (99.985%) was produced after the sponge was subjected to a caustic smelting.
A new process for extracting indium from indium-zinc concentrates was proposed. The process can directly extract indium from removed copper solution by D2EHPA, and cancel the stage of removing iron in the traditional process because of using iron and part of zinc in the In-Zn concentrates for direct preparing high quality Mn-Zn soft magnetic ferrites. The technologies in the processes, such as leaching the neutral leached residues with high concentrated acid at high temperature, reduction ferric and removing copper, and extracting indium, were investigated. The results show that total recovery ratio of indium is increased from less than 70% in the traditional process to more than 95%. This process has the advantages of largely simplifying the procedure of indium extraction, zero draining off of iron residue and zero emitting of SO2. So this is a clean production process.
A hydrometallurgical process has been developed for the recovery of valuable metals from the flue dust of a copper smelter. The dust containing various metals, such as lead, zinc, copper, bismuth, indium, cadmium, iron, arsenic etc., was treated using this hydrometallurgical process to recover all these metals and also to solve environmental pollution problems. Leachings were carried out under atmospheric and elevated pressure utilizing sulfuric acid. Sulfuric acid pressure leaching in the absence of oxygen provided the best separation of copper and arsenic. About 80% of arsenic went into solution during leaching, and more than 90% of copper remained in the residue as cupric sulfide. Zinc, cadmium and indium from the solution and bismuth, copper and lead from the residue were recovered by various well-known processes. Arsenic and iron were removed from the solution by oxidation and precipitation as ferric arsenate. Both laboratory and bench-scale experiments were carried out with satisfactory results.
The distribution of indium (III) between sulphuric, nitric or hydrochloric acid solution and a solution of di-(2-ethylhexyl)-phosphoric acid (DEHPA) or 2-ethylhexyl 2-ethylhexyl-phosphonic acid (EHEHPA) in kerosene has been investigated under various conditions. The organic extracts were examined by infrared and nuclear magnetic resonance spectroscopy. As a result, it was found that the extraction efficiency for indium (III) of DEHPA is higher than that of EHEHPA, and that the effect of the kind of aqueous acid solution on the extraction of indium (III) is in the order HNO3 > H2SO4 > HCl at low aqueous acidity, but that this order becomes the reversed at higher acidity. The extraction by DEHPA shows that the distribution coefficient from sulphuric or nitric acid solutions diminishes monotonically with increasing aqueous acidity, while the distribution coefficient from hydrochloric acid solutions decreases monotonically with increasing aqueous acidity below 1 mol dm-3, and above this, acid concentration rises with acidity up to 5 mol dm-3 and falls again at higher acidities. The extraction curve of EHEHPA resembles that of DEHPA, although the distribution coefficient from hydrochloric acid solutions decreases slightly with aqueous acidity above 1 mol dm-3. The equilibrium equations are proposed on the basis of the results obtained.
The extraction of In(III) from HCl, H2SO4, and HNO3 media using a 0.20moll−1 Cyanex 923 solution in toluene is investigated. In(III) is quantitatively extracted over a fairly wide range of HCl molarity while from H2SO4 and HNO3 media the extraction is quantitative at low acid concentration. The extracted metal ion has been recovered by stripping with 1.0moll−1 H2SO4. The stoichiometry of the In(III): Cyanex 923 complex is observed to be 1:2. The extraction of In(III) is insignificantly changed in diluents namely toluene, n-hexane, kerosene (160–200°C), cyclohexane, and xylene having more or less the same dielectric constants, whereas, it decreases with increasing polarity of diluents such as cyclohexanone and chloroform. The extractant is stable towards prolonged acid contact and there is a negligible loss in its extraction efficiency even after recycling for 20 times. The extraction behavior of some commonly associated metal ions namely V(IV), Ti(IV), Al(III), Cr(III), Fe(III), Ga(III), Sb(III), Tl(III), Mn(II), Fe(II), Cu(II), Zn(II), Cd(II), Pb(II), and Tl(I) has also been investigated. Based on the partition data the conditions have been identified for attaining some binary separations of In(III). These conditions are extended for the recovery of pure indium from zinc blend, zinc plating mud, and galena. The recovery of the metal ions is around 95% with purity approximately 99%.
This review identifies the most significant knowledge acquired on the recovery of indium from aqueous solutions using solvent extraction. Research on the efficient and selective recovery of this valuable element from aqueous solutions is particularly emphasized, as this information is useful for potential hydrometallurgical applications. A good comprehension of the extraction reactions involved can be important for further development; therefore, the data provided are systematically classified according to the different types of chemical reactions that occur during metal ion extraction. Some complexation studies may also be mentioned, particularly if they contribute additional information to a promising solvent extraction system.
Distribution of indium(III), lanthanum(III) and bismuth(III) between sulphuric acid solutions and solutions of di-(2-ethylhexyl)-phosphoric acid (DEHPA) in kerosene has been investigated. The organic phases have been studied by i.r. and NMR spectroscopy. The mechanism of the extractions is discussed.
The extraction of indium(III) and gallium(III) along with the associated metal ions from hydrochloric acid medium by bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex 272) has been studied. The extraction profiles of indium(III) and gallium(III) have been investigated as a function of type and molarity of the acid, nature of organic diluent and concentration of the metal ion and the extractant. The extracting species have been identified as In(OH)R2, Ga(OH)R2 and H+GaCl4·2R. It has been possible to strip In(III) and Ga(III) from the organic phase by appropriate molarity of HCl. Conditions for a number of binary and ternary separations of analytical interest have been optimized. The developed conditions have been extended to recover pure In(III) from sphalerite and galena and Ga(III) from bottom ash and electronic waste. Loading capacity of the extractant was evaluated and the results reveal that Cyanex 272 can hold indium(III) up to one-fifteenth and gallium(III) up to one-twentieth of its molar concentration. The hydrolytic stability and regeneration capacity of the extractant has been assessed.
Indium is an important by-product of zinc metal processing operations. Indium and other metal values are recovered during the production of primary commodities such as zinc by means of complex procedures, many of which are proprietary to each producer. One zinc recovery method consists of the Waelz process followed by leaching and purification prior to electrolytic recovery of zinc as cathodes and subsequent containment of the indium fraction in residues. Related processes for recovery of lead and tin from smelters and refineries also provide indium and other compounds. Indium may be associated with other valuable elements such as vanadium, thallium, gallium and germanium, and cadmium. Typical sulphide-bearing host minerals consist of Sphalerite, Galena, and Chalcopyrite. The igneous intrusions in sedimentary formations may include other base metals such as copper, cobalt, and noble metals consisting of gold, silver, and platinum group metals. The review serves to assimilate the major highlights of this somewhat rare metal which has both strategic importance and is well suited to electronic applications. On a global basis, the writers are aware of 30 producers dedicated to the commercial production of indium metal. Countries such as Belgium, Canada, China, France, Japan, Russia, and the USA are the largest producers of indium while about ten other countries contribute smaller quantities for worldwide consumption. The supply and demand of pure indium products during the past 40 years has been erratic and subject to wide fluctuations in delivered price. The paper describes the sources and established industrial processes for recovery of indium originating from sulphidic materials and process reverts.
The use of alkylphosphoric acids for solvent extraction separations is described, and the use of antisynergic agents for stripping is discussed.