An efficient, simple and lowcost method for purification of zinc sulfate solutions from chloride ions by precipitation with bismuth hydroxosulfate BiOHSO
4
∙H
2
O was proposed. Chemical analysis, ...X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to characterize the solid obtained. The studied parameters were reaction temperature, pH, concentrations of zinc sulfate and chloride, and the molar ratio between BiOHSO
4
∙H
2
O and chloride. Under optimal conditions, the chloride removal efficiency reached 94.5-95.8% and the residual concentration of Cl
−
in the purified solution was 65-85 mg/L, which meets the requirements for zinc electrolysis and allows the production of special high-grade zinc. Compared with the commonly used approaches, the method proposed has the advantages such as a higher degree of purification of zinc electrolyte, the short period of time required for the BiOCl precipitation (1 hour) and good filterability. Apart from that, the consumption of the precipitant is close to the stoichiometric molar ratio, which makes the purification process cost-effective.
Di(2-ethylhexyl)phosphoric acid (D2EHPA, HR) is widely used for solvent extraction of indium from acidic leaching solutions, but indium stripping from the loaded organic phase is difficult because of ...the high affinity of indium for the extractant. Adding proton-donor additives (HA) to the D2EHPA solution is a way to achieve high stripping efficiency for indium. In this work, monocarboxylic acids, aliphatic alcohols, and phenol derivatives were used as additives. Nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy of the organic phases confirm the formation of intermolecular associates (H-complexes) between all additives and D2EHPA. In the case of alcohols and substituted phenols, the interaction of oxygen atoms of alcohols or phenols with the proton of the hydroxyl group of D2EHPA is predominant, while in the case of monocarboxylic acids, an interaction between the hydroxyl proton of the acid and the PO group of D2EHPA mainly occurs. Despite the high In distribution ratio with D2EHPA (100−1000), in all cases investigated the introduction of additives into the organic phase led to an antagonistic extraction effect, however it facilitated efficient In stripping from the loaded organic phase. This effect depends significantly on the type and structure of the additive. Indium extraction in the presence of additives decreases in the series 4-bromophenol >4-t-butylphenol > octanol, 2-ethylhexanol >4-nitrophenol >2-nitrophenol >2,6-di-t-butylphenol, octanoic acid > Versatic 10. Extraction systems containing D2EHPA and 2-ethylhexanol can be used to recover indium from various industrial solutions, in particular, from those derived from lead‑zinc production and from liquid crystal display panel wastes.
•The state of D2EHPA in CCl4 in the presence of proton-donor additives HA was studied.•The interaction between D2EHPA (HR) and HA was shown to occur.•Antagonistic extraction of indium by mixtures of D2EHPA and additives is observed.•D2EHPA and 2-ethylhexanol system is most efficient for In extraction and stripping.
In this paper, we present the data on silver extraction from nitrate solutions with the disulfide of bis(2,4,4-trimethylpentyl)dithiophosphinic acid (L) in toluene. Based on the analysis of the ...extraction data and the IR and electronic absorption spectra of the extracts, it was concluded that silver extraction is due to the formation of the compound (AgNO3)nL in the organic phase, with n = 1–4. In the extracted complexes, the silver ion is chelated to the sulfur atoms, while the nitrate ion is in the outer sphere.
A study of the effect of the solvent on the extraction of AgNO3 with the disulfide showed that solvent extraction efficiency decreases in the series chloroform > toluene > decane > octyl alcohol, which is due to the preferential solvation of the extracted complex by the solvent. A decrease in the extraction of silver when using octyl alcohol resulted from the predominant interaction of the alcohol with the extractant, rather than with the extracted compound.
It was shown that the disulfide can be used to recover silver from nitric acid solutions containing metal impurities (Ni, Cu, Co, Zn, Fe(III), and Na). The degree of silver recovery in one stage was 99.82%, while the separation factors of silver over the impurity metals (βAg/Me) ranged from 30,000 to 400,000 indicating a high selectivity of the extractant towards silver. Almost complete silver stripping from the loaded organic phase is achieved with a mixture of thiourea or ammonium rhodanide and sulfuric acid solutions.
•AgNO3 extraction with the disulfide of CYANEX 301 was studied.•The composition of the extracted complex was found to be (AgNO3)nL, where n = 1–4.•The degree of silver recovery in one stage was 99.82%.•The separation factors of silver over metals (βAg/Me) ranged from 30,000 to 400,000.
In this work, for the first time, zinc extraction from sulfate–chloride solutions containing iron using mixtures of a С7–С9 fraction trialkyl amine (TAA) with a p-alkyl phenol (HP) and monocarboxylic ...acids (HAs) was studied. P-tertbutyl phenol was used as the alkyl phenol, while caprylic acid and the С11–С19 higher fractions of iso-acids (HIAs) were used as the monocarboxylic acids. The main process parameters that provided for high zinc recovery (~98.5–99%) and its separation from iron (βZn/Fe=15–25) were determined.
Two extraction flowsheets for zinc recovery from sulfate–chloride solutions as zinc chloride followed by its conversion to zinc sulfate are proposed. The first one includes zinc extraction with the TAA and alkyl phenol mixture, washing of the extract from impurities and zinc stripping with water. The subsequent zinc concentration and its conversion to the sulfate solution are carried out by extraction with di(2-ethylhexyl)phosphoric acid (D2EHPA). The second flowsheet includes zinc extraction with the TAA and HIA mixture, washing of the extract with water to remove impurities, chloride ion stripping with an alkaline solution, and zinc stripping with a sulfuric acid solution, resulting in the extractant regeneration.
The data obtained for synthetic solutions were confirmed for leach liquors of a sulfide concentrate from the Zimneye deposit (Russia). Zinc extraction was carried out from solutions containing (g/L) 10–12 Zn, 2–4 Cu, 12–15 Fe(III), 40–50 Fe(II), 0.7–0.8 Pb, 80–85 Cl, and 20–80 H2SO4. The composition of the zinc sulfate obtained by both technologies was of the best quality in accordance with the State Standard of Russia.
•Zn extraction with mixtures of a trialkyl amine and organic acids was studied.•The organic acids used were monocarboxylic acids and a para-alkyl phenol.•A high degree of zinc recovery (~98.5–99%) is achieved in a small number of stages.•Two flowsheets for zinc recovery from sulfate–chloride solutions are proposed.•The process developed allows production of a high-quality zinc sulfate.
Extraction is widely used in the hydrometallurgy of nonferrous metals. In addition to such well-known extractants as oxygen-containing organophosphorus or monocarboxylic acids, thio-substituted ...organophosphorus acids in particular, the commercially available extractant CYANEX 301, the active component of which is bis(2,4,4-trimethylpentyl)dithiophosphinic acid (HR), is of interest. This extractant is a sulfur-containing analogue of CYANEX 272 (bis(2,4,4-trimethylpentyl) phosphinic acid). In this review, the state of CYANEX 301 in various solvents in the absence and presence of electron-donor additives, the chemistry of the extraction processes of non-ferrous metals in the HR systems, the compositions of the extracted compounds, stability of the extractant in aggressive media, technological developments, and prospects for using CYANEX 301 in hydrometallurgy of non-ferrous metals are discussed.
The paper presents data on cobalt extraction from sulfate solutions with bis(2,4,4-trimethylpentyl)dithiophosphinic acid (HR) diluted with nonane and kerosene in the presence of electron donor ...additives (L). Trioctyl amine (TOA), trialkyl amine (TAA), trioctyl phosphine oxide (TOPO), trialkyl phosphine oxide (TAPO), tributyl phosphate (TBP), and n-octanol were used as additives.
Using an electronic spectroscopy method, the interaction between cobalt loaded extracts (CoR2) and the additives was first studied. It was shown that, in the presence of the additives, cobalt oxidation decreased in the series TOA≈TOPO>TBP>n-octanol. This is due to a decrease in the HR activity in the presence of L as well as to the interaction between L and the initial cobalt complex resulting in the formation of mixed ligand complexes such as СоR2∙nL, where n=1,2.
Suggestions for prevention of cobalt oxidation in the organic phase containing bis(2,4,4-trimethylpentyl)dithiophosphinic acid are given.
The degree of cobalt extraction decreases in the series HR+TOPO>HR≈HR+n-octanol≫HR+TAA. Both synergistic and antagonistic effects take place in the HR and phosphine oxides mixture, whereas only an antagonistic effect takes place in the systems containing TAA which is due to the interaction between HR and TAA.
The possibility of using the HR and L mixtures for cobalt recovery from sulfate solutions (here the HR+TOPO mixture was examined for the kinetic separation of Co and Ni) and from leach liquors of oxidized nickel ores (using the extraction system based on HR and TAA) has been demonstrated.
•Co extraction by CYANEX 301 in the presence of electron donor additives was studied.•The additives used were TOA, TAA, TOPO, TAPO, TBP, and n-octanol.•Introduction of the additives into the organic phase prevents Co oxidation.•Introduction of the additives into CYANEX 301 results in a decrease in Co extraction.•The degree of cobalt extraction decreases in the series TOPO>n-octanol≫TAA.
The redox processes taking place in the organic phase during cobalt extraction with the mixtures of bis(2,4,4-trimethylpentyl)dithiophosphinic acid (HR, CYANEX 301) and trioctyl phosphine oxide ...(TOPO, CYANEX 921) have been studied. It was shown that CoR
2
stabilization by the phosphine oxide prevents cobalt oxidation with air oxygen as well as with the disulfide of bis(2,4,4-trimethylpentyl)dithiophosphinic acid (R-R). The introduction of TOPO into the extract containing Co(III) dithiophosphinate results in an increase in the rate of cobalt reduction to Co(II). Analysis of the interphase cobalt distribution as well as of the IR and electronic absorption spectra of the extracts showed that cobalt forms a pentacoordinated tetragonal-pyramidal high-spin complex with the dithiophosphinate ions and TOPO with a tetragonal-pyramidal geometry. The base of the pyramid is made up of sulfur atoms while an oxygen atom is on the top. The composition of the complex was found to be CoR
2
·TOPO. Examples of the possible use of the CYANEX 301 and trialkyl phosphine oxide (TAPO, CYANEX 923) mixtures in cobalt extraction technology are given.
Silver chloride extraction from hydrochloric acid solutions with triisobutylphosphine sulfide (CYANEX 471, L) in the presence of organic proton-donor additives (HR) was studied. Both alkyl-, bromo-, ...nitro-substituted phenols, and organic acids of various structures were used as additives. A new synergistic effect (S) was found to take place in the presence of the additives. The degree of the synergistic effect in the systems containing phenols decreases in the series 4-nitrophenol > 4-bromophenol > 4-tert-butylphenol > 2,6-dimethylphenol > 2-methyl-6-cyclohexylphenol > 2,6-bis(tert-butyl) phenol. In the systems containing organic acids, the following series is observed: dinonylnaphthalenesulfonic acid (DNNSA) > 4-tert-butylphenol > caprylic acid > di(2-ethylhexyl)phosphoric acid > bis(2,4,4-trimethylpentyl)phosphinic acid. Based on the analysis of the extraction data and the IR and NMR spectra of the extracts, it was concluded that an increase in the silver extraction with CYANEX 471 in the presence of HR is due to the formation of the compound AgCl∙2L∙HR in the organic phase. It was shown that a mixture of CYANEX 471 and 4-tert-butylphenol can be used for the highly selective extraction of silver from hydrochloric acid solutions containing metal impurities (Ni, Cu, Co, Zn, Fe(III), and Na). The mixtures of CYANEX 471 with alkylphenols or DNNSA, in which the high synergistic effects (S ≥ 10 and ≥ 50, respectively) take place, can efficiently be used for processing different industrial silver chloride solutions.
An IR-spectroscopy method is used to examine the state of nonane diluted bis(2,4,4-trimethylpentyl)dithiophosphinic acid (HR) in the presence of various electron-donor additives (L). Trioctyl amine ...(TOA), n-octanol, trioctylphosphine oxide (TOPO), tributylphosphate (TBP), and triisobutylphosphine sulfide (TIBPS) were used as additives. The formation of hydrogen bonded complexes (H-complexes) via proton transfer and a TOAH
+
R
−
ion pair was shown to occur in the system containing HR and TOA. For the other additives, except n-octanol, during the formation of the H-complexes, hydrogen bonding without proton transfer takes place. In the HR and n-octanol mixture H-complexes having a structure in which the acid exhibits both proton and electron-donor properties are formed. The concentrations of the monomers (C
HR
) and the activity coefficients for the dithiophosphinic acid (γ
HR(tot)
) in the presence of the additives were calculated. It was shown that C
HR
and γ
HR(tot)
depend essentially on the type of additive and that their values decrease when passing from n-octanol to TOA. The strength of the interaction between HR and L decreases in the series TOA > TOPO > TBP > TIBPS > n-octanol. This series coincides with the basicity series of the additives. An antagonistic effect takes place when zinc is extracted with the HR and L mixture, where L is the trialkyl amine (TAA), the trialkyl phosphine oxide (TAPO), TBP, and n-octanol. A decrease in extraction is observed in the series TAA > TAPO > TBP > n-octanol. This series coincides with the series for decreasing HR activity in the presence of additives. Thus a decrease in the extractant activity resulting from the interaction between HR and L is the determinant factor during zinc extraction with bis(2,4,4-trimethylpentyl)dithiophosphinic acid in the presence of the electron-donor additives.
