Mixed solvent systems for the extraction and stripping of iron(III) from concentrated acid chloride solutions

The extraction of concentrated iron(III) from acid chloride solutions has been investigated with methyl isobutyl ketone (MIBK), tri-n-butyl phosphate (TBP), di(2-ethylhexyl) phosphoric acid (D2EHPA), and their mixtures in various proportions, at different acid concentrations. On comparing the extraction of iron(III) with mixed and individual extractant, it was found that both D2EHPA-MIBK and D2EHPA-TBP mixtures exhibit synergism, the latter having better extraction ability. The synergistic coefficients, at different initial acid concentrations for each mixed extractant system, were evaluated and compared. An increase in the concentration of MIBK and TBP in the mixed organic resulted in higher synergistic coefficient. The stripping of iron(III) from loaded D2EHPA was found to increase with the strip feed acid concentration, while from loaded organic mixtures, it initially increased and then decreased. Stripping of iron(III) from D2EHPA-MIBK loaded solvent is better then D2EHPA-TBP. The extracted iron species formed and the stripping reactions have been proposed. Ultraviolet visible spectra of the stripped organic phase support the result and the proposed mechanisms.     

Iron(III) removal from base-metal electrolyte solutions by solvent extraction

The use of a novel synergistic solvent extraction mixture based on an alkylated derivative of 8-hydroxyquinoline (Kelex 100) and di(2-ethylhexyl) phosphoric acid (D2EHPA) for the selective removal of iron(III) from strong sulphuric acid solutions is described. Stripping of the iron from the loaded organic solvent is effected by reacting with hydrogen to reduce iron(III) to iron(II), which subsequently is easily stripped with a weak acid solution. The applicability of the process for iron removal from an actual copper electrolyte is also demonstrated.     

Extraction of acid and iron values from sulphate waste pickle liquor of a steel industry by solvent extraction route

The extraction of sulphuric acid from the actual solutions generated during the process of pickling of steel from a local tube company dealing with the processing of iron and steel tubes using Alamine 336 has been studied in detail. Various parameters were optimised for the maximum extraction of acid such as concentration of organic extractant, time for equilibration, O/A ratio, acid concentration in the feed, temperature for extraction was varied from 30 to 60 °C. Stripping of loaded acid was done with distilled water at 60 °C. Stripping parameters studied were, temperature and time effect on equilibration, O/A ratio, multiple contact of the same strippant with fresh loaded organic. The effects of the numbers of extraction and stripping stages on the extraction and stripping of sulphuric acid recovery are discussed. After the extraction of acid from WPL, iron values in the raffinate were extracted with a binary solvent mixture consisting of MIBK and D2EHPA which shows a synergistic effect on iron extraction.     

Extraction of vanadium from direct acid leach solution of converter vanadium slag

Direct acid leaching of converter vanadium slag by titanium dioxide waste is eco-friendly and efficient, but with low selectivity. This novel technique can result in a vanadium solution which contains chromium(III), aluminium(III), magnesium(II), manganese(II) and high amount of iron(II) and iron(III). Bis (2-ethylhexyl) phosphoric acid (D2EHPA) and tri-butyl-phosphate (TBP) diluted with sulphonated kerosene were applied for vanadium extraction from the multi-element leach solution. The effects of the initial pH, concentration of D2EHPA, ratio of organic to aqueous phase, and the extraction time on the extraction efficiency of vanadium were investigated in saponification and unsaponifiable systems, respectively. The results showed that the vanadium extraction percentage can be up to 97% and the iron extraction percentage can be less than 10% in a thirteen-stage counter-current simulation test and the separation coefficient between vanadium and iron can reach to 109.8. Furthermore, vanadium(IV) can also be separated from other impurities such as aluminium(III), magnesium(II), manganese(II), chromium(III) efficiently. The loaded organic phase was stripped by 184?g?L^?1 sulphuric acid solution in a three-stage counter-current stripping process and with the total vanadium stripping percentage of greater than 99.5%. In the end, the vanadium pentoxide products with a purity of 99.14% were obtained.     

Treatment of Chloride Waste Pickle Liquor by Solvent Extraction for the Recovery of Iron

A systematic study of the extraction of Fe(III) from chloride waste pickle liquor has been investigated using Cyanex 923 diluted with kerosene to recover iron values from the pickle liquor. Various parameters were studied to optimize the conditions for maximum recovery of iron. Extraction increases with increasing concentration of both hydrochloric acid and extractant. The species extracted into the organic phase appears to be HFeCl₂ with 1 M of the solvent. Effect of various salts as additives on Fe extraction was also studied and it was found that addition of NaCl enhanced the extraction about 2.5 times as compared to that without its addition.

Saturated loading capacity was found to be 60.9 g/L Fe in four contacts at O/A of 1. The stripping of Fe(III) with different concentration of hydrochloric acid and nitric acid from the loaded Cyanex 923 was found to increase up to 1 M of both the acids and then decrease with further increase in acid concentration up to 10 M. However, 100% stripping efficiency of Fe(III) was achieved with 0.8 M oxalic acid in two countercurrent stages at an aqueous:organic phase ratio of 3:1. Extraction parameters for maximum extraction of Fe(III) were optimized.     

Statistical Modeling of Zr/Hf Extraction using TBP–D2EHPA Mixtures

In the present work, response surface methodology was employed for the study and prediction of Zr/Hf extraction curves in a solvent extraction system using D2EHPA-TBP mixtures. The effect of change in the levels of temperature, nitric acid concentration, and TBP/D2EHPA ratio (T/D) on the Zr/Hf extraction/separation was studied by the use of central composite design. The results showed a statistically significant effect of T/D, nitric acid concentration, and temperature on the extraction percentage of Zr and Hf. In the case of Zr, a statistically significant interaction was found between T/D and nitric acid, whereas for Hf, both interactive terms between temperature and T/D and nitric acid were significant. Additionally, the extraction curves were profitably predicted applying the developed statistical regression equations; this approach is faster and more economical compared with experimentally obtained curves.     

The preparation of high purity iron compounds by solvent extraction with aliphatic monocarboxylic acids

The paper gives experimental results for isolating high purity iron(III) chloride by extraction with aliphatic monocarboxylic acids. The feed solutions derive from chlorinated iron scrap and from prepurified iron powder respectively dissolved in hydrochloric acid.The initial solutions containing iron and various metal impurities are contacted with a solvent consisting of the sodium salts of a monocarboxylic acid mixture. The loaded solvent containing iron is scrubbed with an aqueous solution of pure iron(III) chloride. Iron(III) is recovered from the scrubbed solvent by acid stripping. Data are presented to illustrate the influence of various parameters on the extraction system. A mixer-settler system and the conditions under which the process is operated are described.     

Solvent extraction of rhodium from aqueous solution of Rh(III)–Sn(II)–Cl system by TBP

In this paper, the results of a systematic study on the solvent extraction of rhodium with TBP in hydrochloric acid are given. The optimum extraction conditions are as follows: The amount of added stannous chloride is four times that of Rh according to the mole ratio of Sn and Rh, the temperature of complex reaction 60°C, aging time 2 h, phase ratio 1:1, contact time 5 min. A highly efficient method of stripping Rh from the loaded organic phase of TBP is also proposed. The percentage of stripping may reach to 100% through one stage with 4 M hydrochloric acid containing chlorine. The mechanism of extracting Rh(III) with the addition of stannous chloride is described and the reaction equation of extraction is deduced.     

Extraction of chromium (III) from spent tanning baths

Extraction of chromium(III) from a model spent tanning bath of the leather industry has been investigated using ammoniated and non-ammoniated di(2-ethylhexyl)phosphoric acid (D2EHPA) and bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex® 272). Chromium extraction of 95% by 15% (v/v) D2EHPA, 10% (v/v) isodecanol in kerosene and 86.1% by 15% (v/v) Cyanex® 272, 10% (v/v) p-nonylphenol in kerosene was obtained at equilibrium pH values of 4.0 and 5.0, respectively. The separation of small amounts of iron (III) and aluminium (III) present in the solution along with the Cr(III), was also examined and it was found that Cyanex® 272 was a better reagent than D2EHPA. The slow kinetics of extraction and stripping observed in the case of AI(III) was advantageous for its separation from Fe(III) at low pH values. Difficulties faced in the stripping of loaded metals were also studied because only about 80% chromium recovery by 8 M HCl was obtained from both solvents. The incomplete stripping of the metal may be a result of the formation of a stable species in the organic phase and needs further investigation. The Cr(III) can be recovered as chloride from the strip liquor and recycled for retanning purposes.     

A comparative study on extraction of Fe(III) from chloride leach liquor using TBP, Cyanex 921 and Cyanex 923

A comparative study on extraction of Fe(III) from the HCl leach liquor of low grade iron ore tailings has been carried out using Tri-n-butyl phosphate (TBP), Cyanex 921 and Cyanex 923 in distilled kerosene. The percentage extraction of iron increased with increasing HCl and extractant concentrations. The extracted species in each case was found to be HFeCl₄·S. The extraction isotherms for the above extractants indicated quantitative extraction of Fe(III) in 3-stages at O:A ratio of 3:2 with TBP, and in 2-stages at O:A ratio of 1:1 with Cyanex 921 and Cyanex 923. The stripping studies of the loaded organic phases were carried out with 0.4 M HCl. The stripping isotherms indicated 2-stages at O:A ratio of 5:2 for TBP, and 3-stages at O:A ratio of 2:3 for Cyanex 921 and Cyanex 923. From the extraction studies, the extraction efficiency of the extractants for Fe(III) was in the order TBP < Cyanex 921 < Cyanex 923. Although Cyanex 923 was found to be the best extractant, the percentage stripping of Fe from the loaded Cyanex 923 was the least. The stripping of Cyanex 923 was 94.9%, but with TBP and Cyanex 921, it was 99.8% and > 99.9%, respectively.     

TOA-TBP从铁合金萃钯余液中协同萃取分离铂

以等离子炉富集产出的铂钯铑铁合金溶解造液萃钯后的余液为原料,选择TOA-TBP混合萃取剂萃取分离铂。研究单一TBP、TOA以及混合体系对铂的萃取行为。结果表明,对于贱金属较高的溶液体系,100%TBP对铂的萃取率仅有80.9%,单一TOA在高浓度下铂的萃取率接近100%,但铑的共萃率也随之上升,最高可达到82.86%。而95%TBP-5%TOA的混合体系在0.5 mol/L HCI,相比为1,旋转速度100 r/min条件下,铂的萃取率达到99.9%以上,铑的共萃率仅为0.2%。选择稀盐酸洗涤负载有机相,10 mol/L盐酸反萃,铂的反萃率达到97.2%。TOA-TBP混合体系可以实现铂铑高效分离,且该体系对铂的萃取具有协同效应。     

Study on a novel flat renewal supported liquid membrane with D2EHPA and hydrogen nitrate for neodymium extraction

The Nd(III) extraction in flat renewal supported liquid membrane(FRSLM),with polyvinylidene fluoride membrane and renewal solution including HNO3 solution as the stripping solution and di(2-ethylhexyl) phosphoric acid(D2EHPA) dissolved in kerosene as the membrane solution,was investigated.The effects of pH in the feed phase,volume ratio of membrane solution to stripping solution,concentra-tion of HNO3 solution and concentration of carrier in the renewal phase on extraction of Nd(III) were also studied,respectively.As a result,the optimum extraction conditions of Nd(III) were obtained when concentration of HNO3 solution was 4.00 mol/L,concentration of D2EHPA was 0.100 mol/L,and volume ratio of membrane solution to stripping solution was 1.00 in the renewal phase,and pH was 4.60 in the feed phase.When initial concentration of Nd(III) was 2.00×10-4 mol/L,the extraction percentage of Nd(III) was up to 92.9% in 75 min.     

DIBK-P350和DIBK-TOPO负载有机相中铪和锆的反萃

分别以盐酸、硫酸、碳酸氢铵、碳酸铵和碳酸钾的水溶液为反萃剂,对比研究了其对DIBK-P350体系和DIBK-TOPO体系负载有机相中铪和锆的反萃性能。结果表明,盐酸、硫酸、碳酸氢铵和碳酸钾对这两个体系负载有机相中铪和锆的反萃率或分离系数较低,不适合作为该体系的反萃剂,而碳酸铵((NH_4)_2CO_3)较适合作为反萃剂。在室温、油水相比O/A=1/2、(NH_4)_2CO_3浓度1.5~2.0mol/L的优化条件下,DIBK-P350体系负载有机相中(NH_4)_2CO_3对铪的单级反萃率和锆铪的分离系数分别达到91.61%和6.94。对DIBK-TOPO体系负载有机相反萃的优化条件为:室温、油水相比O/A=1/2、(NH_4)_2CO_3浓度2.0 mol/L,(NH_4)_2CO_3对铪的单级反萃率和锆铪的分离系数分别达94.33%和15.30。     

用三烷基氧化膦从氰化浸出液中萃取低浓度金

研究了三烷基氧化膦(TRPO)-磷酸三丁酯(TBP)-煤油萃取体系对氰化浸金液中低浓度金(Ⅰ)的萃取和反萃取能力,结果表明,尽管TRPO体系中添加TBP对金(Ⅰ)的萃取率影响很小,但一定量的TBP能提高体系的反萃效果。考察了料液pH值、硫酸锂浓度等因素对萃取率的影响,探讨了不同的反萃温度、反萃相比对负载有机相中金(Ⅰ)的反萃效果。结果表明,采用TRPO-TBP-煤油组成的有机相,对金(Ⅰ)质量浓度为9.5 mg/L、盐析剂硫酸锂浓度为1.0 mol/L的碱性氰化液在相比A/O=1∶1条件下进行萃取时,金(Ⅰ)的单级萃取率可达95%以上;反萃温度越高,相比(A/O)越大,反萃效果越好,可以将大部分金(Ⅰ)反萃出来。     

A study of the leaching of copper and zinc from a greek copper concentrate. Liquid-liquid extraction for the separation of copper,zinc and iron from the leach solutions

This study is an investigation of the extraction of copper and zinc from a mixed sulphide concentrate by means of a conventional hydrometallurgical process, which was carried out in four stages: (a) catalytic sulphation roasting, (2) water leaching of the metallic values, (3) solvent extraction, and (4) selective stripping.More particularly, this investigation determined: (a) the roasting conditions favorable for the formation of the maximum amount of soluble copper and zinc sulphates; (b) the solvent extraction of iron and zinc from the leach solutions, applying the organic reagent D2EHPA diluted by cyclohexane or kerosene as a solvent; (c) the optimum conditions of selective stripping offering the ability to separate iron and zinc; and (d) the enrichment abilities of the electrolytes suitable for the electrowinning of the metals.     

DIBK协萃体系负载有机相反萃行为研究

以不同酸度的盐酸和硫酸为反萃剂从DIBK-TBP体系和DIBK-P204体系负载有机相中反萃锆、铪。结果表明,对DIBK-TBP体系负载有机相,先采用酸度为2.0mol/L的盐酸水溶液对锆进行反萃,单级反萃率达85%,得到富锆液,然后用酸度为8.0mol/L的硫酸水溶液对铪进行反萃,单级反萃率达90%,得到少锆的铪液;对DIBK-P204体系负载有机相,先采用酸度为3.0mol/L的硫酸水溶液对铪进行反萃,单级反萃率达90%,得到少锆的铪液,然后采用酸度为2.0mol/L的盐酸水溶液对锆进行反萃,单级反萃率达70%,得到少铪的锆液。采用盐酸和硫酸可顺利实现对DIBK体系负载有机相中锆、铪的反萃取。     

Recovery of yttrium from deep-sea mud

Deep-sea mud rich in rare earth yttrium has received lots of attention from the international community as a new resource for Y. A novel process, which mainly includes acid leaching, solvent extraction, and oxalic acid precipitation-roasting, is proposed for recovery of Y from deep-sea mud. A series of experiments were conducted to inspect the impacts of various factors during the process and the optimum conditions were determined. The results show that the Y of deep-sea mud totally exists in apatite minerals which can be decomposed by hydrochloric acid and sulfuric acid solution. The highest leaching efficiency of Y is 94.53% using hydrochloric acid and 84.38% using sulfuric acid under the conditions of H~+concentration 2.0 mol/L, leaching time 60 min, liquid-solid ratio 4:1 and room temperature 25 ℃(only in case of sulfuric acid, when using hydrochloric acid, the leaching temperature should be 60 ℃). Because of the much lower leaching temperature, sulfuric acid leaching is preferred. The counter current extraction and stripping tests were simulated by a cascade centrifugal extraction tank device. Using 10 vol% P204,15 vol% TBP and 75 vol% sulfonated kerosene as extractant, 98.79% Y~(3+) and 42.60% Fe~(3+) are extracted from sulfuric acid leaching liquor(adjusted to pH = 2.0) after seven-stage counter current extraction with O/A ratio of 1:1 at room temperature, while other metals ions such as Al~(3+), Ca~(2+), Mg~(2+)and Mn~(2+) are almost not extracted. The Y~(3+) in loaded organic can be selectively stripped using 50 g/L sulfuric acid solution and the stripping efficiency reaches 99.86% after seven-stage counter current stripping with O/A ratio of 10:1 at room temperature, while only 2.26% co-extracted Fe~(3+) is stripped. The Y~(3+) of loaded strip liquor can be precipitated by oxalic acid to further separate Y~(3+) and Fe~(3+). The precipitation efficiency of Y~(3+) in loaded strip liquor can be 98.56% while Fe~(3+) is not precipitated under the conditions of oxalic acid solution concentration 200 g/L, quality ratio of oxalic acid to Y of 2, and precipitation time 0.5 h. And the precipitate was roasted at 850 ℃ for 3 h to obtain the oxide of Y in which the purity of Y_2 O_3/REO is 79.02% and the contents of major non-rare earth impurities are less than 0.21%.Over the whole process included acid leaching, solvent extraction, and oxalic acid precipitation-roasting,the yttrium yield is 82.04%.     

Uranium extraction from partially neutralised and diluted phosphoric acid using a synergistic organophosphorous solvent mixture

A process is described for the separation of uranium from partially neutralised and diluted phosphoric acid (PNDA) which is generated in fertiliser plants when phosphoric acid is used to scrub ammoniacal vapours from the neutralisation reactors. The separation process is based on solvent extraction using a synergistic mixture of di-2-ethyl hexyl phosphoric acid (DEHPA) with tri-n-alkyl phosphine oxide (TAPO). The effects of process parameters including concentration of DEHPA and TAPO, temperature and degree of neutralisation of acid have been investigated. Laboratory scale and pilot plant scale tests have been carried out. The extraction reaction is found to be exothermic with enthalpy effect of 30 kJ/mol. Tests on stripping of extracted uranium and recovery of uranium have been carried out and results are reported. Analysis of data indicates significant differences in the mechanism of uranium extraction from PNDA and the mechanism reported in literature for extraction of uranium from weak phosphoric acid using a similar solvent mixture.     

Removal/recovery of hydrochloric acid using Alamine 336, Aliquat 336, TBP and Cyanex 923

Solvent extraction of hydrochloric acid has been studied from solutions containing 185.42 g/L acid using Alamine 336, Aliquat 336, TBP and Cyanex 923 as extractants. Kerosene was used as the diluent. Extraction of hydrochloric acid increased with the increasing concentration of the extractants. For all the extractants studied, the species extracted into the organic phase appears to be associated with one mole of extractant. For Alamine 336, the McCabe–Thiele construction indicated the possibility of > 99.5% HCl extraction in two counter-current stages at A:O = 1:4. For Cyanex 923, the McCabe–Thiele construction indicated the quantitative extraction of HCl in four counter-current stages at the A:O = 1:5 phase ratio. The acid loaded onto Aliquat 336, TBP and Cyanex 923 could be easily stripped with water. But acid loaded onto Alamine 336 could not be stripped with water. The stripping efficiency was ∼ 12% with dilute acid and quantitative with 1 N NaOH for acid loaded onto Alamine 336.     

Processing of nickel- and cobalt-containing leach liquors obtained from different raw materials

Acidic as well as ammoniacal leach liquors obtained from three different raw materials, namely, lateritic nickel ores, copper converter slag and Indian Ocean manganese nodules, were treated for removal of impurities and separation of copper, nickel and cobalt. Precipitation and solvent extraction techniques were used for these purposes. Iron and silica impurities from acidic solutions were removed by lime precipitation. In ammoniacal medium, iron was coprecipitated with manganese. Manganese was removed as manganese dioxide by oxidative precipitation from both media; this removal also results in some loss of cobalt due to its adsorption on the manganese dioxide matrix. From sulphate solutions, copper was extracted using LIX 64N^®1 followed by nickel-cobalt coextraction using di-2-ethylhexylphosphoric acid (D2EHPA). From the loaded solvent, nickel and cobalt were separated by the crowding technique. From ammoniacal solution, both copper and nickel were coextracted with LIX 64N and separated by selective stripping from the loaded organic phase. Cobalt was recovered either by sulphide precipitation or by adsorption on lignite followed by desorption with sulphuric acid/spent electrolyte.