Removal of Fe(III) from Ni-Co-Fe chloride solutions using solvent extraction with TBP

Journal Pre-proof Removal of Fe(III) from Ni-Co-Fe chloride solutions using solvent extraction with TBP

Xintao Yi, Guangsheng Huo, Wei Tang PII:

S0304-386X(19)30728-5

DOI:

https://doi.org/10.1016/j.hydromet.2020.105265

Reference:

HYDROM 105265

To appear in:

Hydrometallurgy

Received date:

15 August 2019

Revised date:

14 December 2019

Accepted date:

17 January 2020

Please cite this article as: X. Yi, G. Huo and W. Tang, Removal of Fe(III) from NiCo-Fe chloride solutions using solvent extraction with TBP, Hydrometallurgy(2019), https://doi.org/10.1016/j.hydromet.2020.105265

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

© 2019 Published by Elsevier.

Journal Pre-proof

Removal of Fe(III) from Ni-Co-Fe chloride solutions using solvent extraction with TBP Xintao Yia, Guangsheng Huoa,b,* a

[email protected], and Wei Tanga

School of Metallurgy and Environment, Central South University, Changsha 410083, China

b

National Engineering Laboratory for High Efficiency Recovery of Refractory Nonferrous Metals,

Central South University, Changsha 410083, China *

Corresponding author.

Abstract The extraction of Fe(III), Ni(II) and Co(II) from a Ni(II)-Co(II) solution containing Fe(III) was analyzed in a chloride medium using a mixed extractant consisting of 50% (v/v) tributyl phosphate

of

(TBP), 20% (v/v) 2-octanol and 30% (v/v) kerosene. The extraction of 0.5 mol/L Fe(III) in 4 mol/L hydrochloric acid reached 97%, and the consumption of chloride ions was investigated. Nickel(II) ions

ro

were not detectably extracted by TBP, with an inclusion of less than 1.1%. Compared with Fe(III), TBP extracted only a small amount of Co(II). The iron complexes formed by TBP and 2-octanol were

-p

[H2FeCl4 · 2TBP] and [H2FeCl4 · 5(2-octanol)], and the possible compositions of Co-containing extracts were [H2CoCl4 · 2TBP] and [H2CoCl4] · n[2-octanol]. An industrial process consisting of

re

two-step extraction was designed to achieve the separation of Co(II) and Fe(III), resulting in a decrease in the Fe/Co mass ratio from 0.46 to less than 3.5×10-4 in the raffinate.

lP

Keywords: Fe(III), Ni(II), Co(II), Tributyl phosphate, 2-Octanol, Industrial process 1. Introduction

na

Nickel and cobalt are strategic resources that have been widely used as battery materials (Fernandes et al., 2013), cemented carbide (Hanner et al., 2018), catalysts (Bao et al., 2019), medicines (Cárdenas-Triviño et al., 2017), pigments (Gaudon et al., 2014) and permanent magnet materials

Jo ur

(Orefice et al., 2019). However, the leaching of iron is inevitable when nickel laterite ore (Ribeiro et al., 2019; Zhai et al., 2010) and cobalt ore are subjected to an acid treatment. The treatment of industrial materials such as waste cemented carbide and spent catalysts is also faced with the problem of treating a mixed nickel-cobalt-iron solution. Therefore, a method that effectively separates iron from nickel and cobalt must be developed.

Compared with traditional precipitation methods for iron removal, such as the goethite method, the hydrolysis method, the jarosite method, etc., solvent extraction has the advantages of high selectivity, low pollution, and low energy consumption. Acidic organophosphorus esters, amine extractants, carboxylic acid extractants and neutral organophosphorus reagents have been studied in iron separation. The acidic organophosphorus reagent P204 (Li et al., 2009) separates the iron from a nickel-cobalt solution by controlling the pH value, but it is difficult to strip (Yu and Chen, 1989) and reach equilibrium extraction. Sun et al. (2016) investigated the separation of ferric ions from an aluminum solution using N235 and P204, and reported iron removal and stripping percentages greater than 97% and 99%, respectively. Shen et al. (2008) reported the effective separation of cobalt and nickel in a chloride solution using N235. The extraction system consisting of the primary amine N1923, n-octanol and kerosene removed 99.99% of iron from industrial aluminum sulfate as an iron(III) hydroxyl-sulfate complex at pH > 1.2 (Li et al., 2011).

Journal Pre-proof The solvent extraction systems that are typically studied are systems composed of neutral organophosphorus and a high concentration of hydrochloric acid. Mishra et al. (2010) reported the extraction and stripping efficiency of the extractants for iron in the order TBP < Cyanex921 < Cyanex 923

and

Cyanex923

<

TBP

<

Cyanex921.

The

extracted

species

appeared

to

be

H2FeCl4·2TBP/H2FeCl4·2Cyanex 923/H2FeCl4·2Cyanex 923. The mixture of 70% (v/v) TBP and 30% (v/v) MIBK (Reddy and Sarma, 1996; Saji and Reddy, 2001; Sarangi et al., 2007) has been extensively analyzed because of its faster phase separation and efficient extraction capacity. However, few reports have described in detail the separation of iron in a nickel-cobalt-iron system using TBP. In the present study, TBP was used in the extraction of iron from a nickel-cobalt solution and MIBK was replaced with the more economical and common modifier 2-octanol, which sufficiently solved the three-phase and emulsification problems of TBP (Zhou et al., 2019). The extraction mechanism of Fe(III),

of

Ni(II)and Co(II) was also investigated. A process flowsheet has been designed based on the results of

ro

the fundamental experiments. 2. Experimental

-p

2.1 Reagents and apparatus

The primary extractant TBP (99%) and secondary extractant octanol (97%) were purchased from Shanghai Aladdin Biochemical Technology Co. Ltd., China. Kerosene was provided by Tianjin

re

Hengxing Chemical Preparation Co. Ltd., China. The aqueous solution was prepared by dissolving FeCl3 · 6H2O, CoCl2 · 6H2O or NiCl2 · 6H2O in concentrated HCl and diluting the mixture with

lP

deionized water. The industrial solution used for the recovery of nickel and cobalt was provided by a solid waste recycling company in Hunan China.

Inductively coupled plasma-optical emission spectrometry (ICP-OES, Thermo Electron Optimal

na

7000) was used to analyze the metal concentrations in a mixed solution. An ion chromatograph (DIONEX ICS-90) was used to analyze the concentration of Cl- in the iron solution. A Fourier

Jo ur

transform infrared (FT-IR) spectrometer (Thermo Scientific Nicolet IS 10) was used to analyze the presence of Fe/Ni/Co in the extractant.

2.2 Extraction and stripping procedures Solvent extraction and stripping experiments were performed by mechanically shaking the organic and aqueous phase in separatory funnels of a suitable volume at 298 K. Based on the results from preliminary experiments, extraction equilibrium was attained within 5 min. The metal concentrations in the organic phase were calculated by determining the mass balance. The metal extraction extent qe (%) and the stripping extent qs (%) were calculated using the following equations: qe=1‐

C𝑟 × Vr

C𝑖𝑛𝑖 × Vini

qs=

Cs × Vs q𝑒 ×C𝑖𝑛𝑖 × Vini

where Cini, Cr and Cs represent the concentrations of Fe, Ni and Co in the initial liquid, raffinate and stripping solution, respectively (mol/L); and Vini, Vr and Vs represent the volumes of the initial liquid, raffinate, and stripping solution, respectively (L). 2.3 Analysis of Cl- consumption The concentration of chloride ions in the feed and raffinate solution could be analyzed by ion

Journal Pre-proof chromatograph and the difference in concentration before and after extraction was the consumption of Cl-. The amount of iron extracted into the organic phase in the stock solution could be calculated by mass conservation. Therefore, based on the coordination of four chloride ions by one iron ion (formula 2), the amount of Cl- extracted by TBP and 2-octanol in the form of HFeCl4 could be calculated in the feed. The remaining consumption of Cl- was extracted in the form of hydrochloric acid (formula 3). The consumption of Cl- could be calculated according to the following equation: S=C0‐

C1 × Vr Vini

S1=4×Cini×qe S2=S- S1 Where S is the total consumption of Cl- (mol/L); S1 is the consumption of Cl- in the form of

of

HFeCl4 (mol/L); S2 is the consumption of Cl- in the form of HCl (mol/L); C0 is the initial concentration of Cl- (mol/L); C1 is the concentration of Cl- in raffinate (mol/L); Vini, Vr and qe are synonymous with

ro

the symbols in Section 2.2. 3. Results and discussion

-p

3.1 Extraction of Fe3+

3.1.1 Effects of H+ and Cl- concentrations in the feed

re

The extraction of Fe3+ with 50% (v/v) TBP and 20% (v/v) 2-octanol was investigated in the presence of different H+ and Cl- concentrations. The extraction gradually increased with increasing

lP

acidity, as shown in Fig. 1. For example, the extraction of Fe3+ was approximately 2% in the presence of 0.1 mol/L H+ and 1.44 mol/L Cl-, and the value slowly increased to 25.5% as the acidity was increased to 4 mol/L H+. Similarly, the extraction of Fe3+ increased from 54.9% in the presence of 0.1

na

mol/L H+ to 96.9% in the presence of 4 mol/L H+ when the concentration of Cl- was 5.4 mol/L. Compared with the effect of the H+ concentration, that of the Cl- concentration played a more important

Jo ur

role in the extraction. The extraction increased from 2% in the presence of 1.4 mol/L Cl- to 55% in the presence of 5.4 mol/L Cl- at a concentration of 0.1 mol/L H+. In the presence of 4 mol/L H+, the extraction displayed an increase of approximately 72% as the concentration of Cl- was increased. In the hydrochloric acid solution, the neutral extractant TBP first forms an oxonium salt (Gaikwad, 2004) with the hydrogen ion, as represented by Formula (1), before interacting with the anion: H++TBPor = [TBPor · H]+

(1)

-

Therefore, when the concentration of Cl is the same, an increase in the concentration of H + improves the extraction. The ionic forms of iron present in the hydrochloric acid solution are Fe 3+, FeCl2+, FeCl2+, FeCl3 and FeCl4-, among others (Lee et al., 2004). As the concentration of chloride ions increases, the proportion of the FeCl4- content increases. When the FeCl3 concentration is less than 1.0 mol/L and the HCl concentration is less than 3.5 mol/L, FeCl4- is extracted, as shown in Formula (2): Fe3++4Cl-+H++2TBPor = HFeCl4 · 2TBPor Therefore, the chloride ion concentration determines the ability of TBP to extract iron.

(2)

ro

of

Journal Pre-proof

3.1.2 Consumption of Cl-

re

-p

Fig. 1 Effects of H+ and Cl- concentrations on Fe3+ extraction (feed: 26 g/L Fe3+; O/A=2)

TBP not only extracted iron but also extracted hydrochloric acid (Sarangi et al., 2006) in the

lP

chloride solution, as shown in Formula (3).

HCl+TBPor = HCl · TBPor -

(3)

3+

By analyzing the concentrations of Cl and Fe before and after extraction, the authors plotted the

na

changes of chloride ion content in the feed extracted into the organic phase in the form of HFeCl4 and HCl at different HCl concentration. As shown in Fig. 2, region ① and region ② represented the

Jo ur

amount of chloride ions consumed in the form of HFeCl 4 and HCl, respectively. Corresponding to an extraction extent of only 2% in the presence of 0.1 mol/L HCl, the loss of chloride ions in the solution was negligible. In the presence of 1 mol/L HCl, about 90% of the extracted chloride ions in the feed were in the form of FeCl4-, where the molar ratio of FeCl4- to HCl was 2. With the increase of HCl concentration, the consumption of Cl- increased rapidly with the increase of iron extraction, and the area occupied by regions ① and ② was getting bigger. However, although FeCl4- was still the predominant form of Cl- consumption, more and more HCl was extracted into the organic phase. In the presence of 4 mol/L HCl, 21.2% of the extracted chloride ions represented by region ② were in the form of HCl, and the molar ratio of FeCl4- to HCl was only 0.9.

-p

ro

of

Journal Pre-proof

re

Fig. 2 Effects of the HCl concentration on the consumption of Cl- and Fe3+ extraction (feed: 26 g/L Fe3+;

lP

O/A=2：1) 3.1.3 Fe3+ extraction distribution isotherm

The extraction distribution isotherms and McCabe-Thiele diagrams for 50% (v/v) TBP and 20%

na

(v/v) 2-octanol extractants in 30% (v/v) kerosene containing various concentrations of HCl are shown in Fig. 3. The saturated capacity of Fe3+ extraction reached 15.0 g/L, 23.9 g/L and 33.3 g/L in the presence of 2, 3 and 4 mol/L hydrochloric acid, respectively. In addition, most of the iron was extracted

Jo ur

in two and three theoretical extraction stages at an O/A ratio of 2:1 in the presence of 4 and 3 mol/L hydrochloric acid, respectively. At the same time, graded extraction in the presence of 2 mol/L hydrochloric acid is unnecessary.

-p

ro

of

Journal Pre-proof

Fig. 3 Fe3+ extraction distribution isotherm and the McCabe-Thiele diagram for extraction with 50%

re

(v/v) TBP and 20% (v/v) 2-octanol at 25°C in the presence of different HCl concentrations 3.1.4 Stripping of Fe3+ from the loaded organic phase

lP

The stripping behavior of iron from the loaded TBP was investigated by varying the pH and the O/A ratio. As shown in Fig. 4, the iron stripping remained basically unchanged and exceeded 92% as the pH decreased at an O/A ratio of 2:1. The O/A ratio had a greater impact on the stripping. The

na

stripping of Fe3+ reached 98% at an O/A ratio of 1:1, a value that is much larger than the stripping of 57% and 71% observed at O/A ratios of 4:1 and 3:1, respectively. Therefore, distilled water with an O/A

Jo ur

ratio of 2:1 was adopted as the stripping agent, due to its economy and convenience.

Fig. 4 Stripping of Fe3+ from the loaded organic phase by solutions with different pH values and O/A

Journal Pre-proof ratios (25 g/L Fe3+ loaded) 3.2 Extraction of Ni2+ and Co2+ Similar to ferric chloride, the ionic forms of cobalt in hydrochloric acid solution are Co2+, CoCl+, CoCl2, CoCl3-, and CoCl42-. With increasing HCl concentrations, the molar fraction of cobalt chloride complexes decreased in the order: Co2+ > CoCl+ > CoCl3- > CoCl2 > CoCl42-(Lee and Oh, 2005). Although the properties of nickel are similar to cobalt, nickel is mainly present in the form of Ni2+, NiCl+ and NiCl2 in solutions with high-chlorine concentrations. Researchers have not conclusively determined whether NiCl3- and NiCl42- are present in a hydrochloric acid solution (Rongsun et al., 1983). The extraction of cobalt and nickel was studied in the presence of different hydrochloric acid concentrations. As shown in Fig. 5, the extraction of cobalt increased from 1.5% to 28.7% as the HCl

of

concentration was increased from 1 to 8 mol/L. Moreover, as the concentration of HCl increased, the color of the initial solution and the organic phase became bluer. The reaction formula (Qixiu et al.,

ro

2014) is expressed as follows:

Co2++2H3O++4Cl-+2TBP=[H3O · TBP]2 · [CoCl42-]

(4)

-p

In contrast to cobalt, the extraction of nickel was almost constant, and the color of the organic phase did not change. Thus, TBP is unable to extract nickel, and the extraction of nickel is considered an inclusion. (The controversial NiCl3- and NiCl42- anions are unlikely to achieve an extraction of

Jo ur

na

lP

re

approximately 1%.)

Fig. 5 Effects of HCl concentrations on Ni2+ and Co2+ extraction (feed: 30 g/L Co2+, 30 g/L Ni2+; O/A=2) 3.3 Separation of Fe3+ from Ni2+ and Co2+ Nickel-cobalt-iron solutions with different concentrations in 4 mol/L HCl were prepared to study the extraction of nickel-cobalt in iron solutions. As shown in Fig. 6, the extraction of iron were higher than 98%. With the increasing concentrations of nickel chloride and cobalt chloride, the iron extraction increased slightly and the extraction of low concentration iron solution was higher than that of high

Journal Pre-proof concentration. Due to the nature of nickel being almost unextracted, the inclusion of nickel in the two iron solutions was approximately the same at 1.1%. Compared with nickel, cobalt extraction presented different trends. Since a higher concentration of cobalt results in a greater proportion of cobalt anions at a constant molar ratio of cobalt to chlorine, cobalt extraction increased as its concentration increased. Therefore, the cobalt extraction increased from 1.2% to 3.4% in the 5 g/L iron solution and from 1% to 1.5% in the 25 g/L iron solution. However, since cobalt had a lower affinity for TBP than iron and the H2CoCl4 extracted by the organic solvent was gradually replaced with HFeCl4 as the iron concentration increased, the extraction of cobalt in the 25 g/L iron solution was much lower than that in the 5 g/L iron

Jo ur

na

lP

re

-p

ro

of

solution.

Fig. 6 Extraction of different concentrations of Fe(III)-Ni(II)-Co(II) solutions (left: Co and Ni in 5 g/L Fe solution; right: Co and Ni in 25 g/L Fe solution) 3.4 Analysis of IR spectra FT-IR spectroscopy was performed in the range of 400-4000 cm-1 to investigate the extraction of complexes of Fe(III), Ni(II) and Co(II) with 50% (v/v) TBP and 20% (v/v) 2-octanol. The extractants loaded with HCl and metal ions were compared with the untreated extractant (Fig. 7). Table 1 lists the characteristics peaks and the likely assignments. The asymmetric/symmetric stretching and bending vibration of -CH3 and carbon chain vibrations of CH2 and P-O-C produced characteristic peaks at 2958/2873, 1461/1376, 2927/2858, and 1025/995 cm-1, respectively (Zhou et al., 2019), and the peaks were unchanged during the extraction. The peak at 1257 cm-1, which is attributed to the vibration of the P=O group in TBP, changed after extraction, indicating that the phosphoryl oxygen atom coordinated with the solute during the extraction process. The peaks at 1249, 1230 and 1245 cm-1 in TBP were attributed to the vibration of P=O · HCl, P=O · H2CoCl4 and P=O · HFeCl4, respectively. Since nickel was generally not extracted, its characteristic peak was the same as that in the spectrum of the

Journal Pre-proof HCl-loaded extractant. 2-Octanol also displayed little extractability. The peak at 1103 cm-1, which is associated with C-O vibrations in the 2-octanol, remained unchanged after extraction, suggesting that the hydroxyl functional group was not altered and that the extraction reaction occurred in the form of an oxonium ion. Therefore, the characteristic peak for –OH was located at 3444 cm-1, and the peaks at 3413, 3359 and 3386 cm-1 were attributed to –OH · HCl, -OH · H2CoCl4 and –OH · HFeCl4 (Wang et al., 2016), respectively. Similar to TBP, the almost complete lack of extraction of nickel by 2-octanol was masked by the characteristic peak of hydrochloric acid. In summary, the extraction of iron and cobalt from HCl-containing medium using TBP and 2-octanol is expressed as follows: 2HFeCl4+2TBPor+5(2-octanol)=[HFeCl4 · 2TBPor]+[H2FeCl4 · 5(2-octanol)]

(6)

of

2H2CoCl4+2TBPor+n(2-octanol)=[HCoCl4 · 2TBPor]+[H2CoCl4] · n[2-octanol]

(5)

Table 1 Wavenumber (cm-1)

assignment

HCl·org

2958, 2873

2958, 2873

1461, 1376

1461, 1376

2927, 2858

2927, 2858

ν P-O-C, ν P-O-C

1025, 995

ν P=O

1257

ν -OH

3444

as

s

as

s

δ CH3-, δ CH3ν -CH2-, ν -CH2as

as

s

1103

HFeCl4·org

2958, 2873

2958, 2873

2958, 2873

1461, 1376

1461, 1376

1461, 1376

2927, 2858

2927, 2858

2927, 2858

1025, 995

1025, 995

1025, 995

1025, 995

1249

1249

1230

1245

3413

3413

3359

3386

1103

1103

1103

1103

Jo ur

na

ν C-O

H2CoCl4·org

lP

ν C-H, ν C-H

H2NiCl4·org

re

org

s

-p

Probable as

ro

Characteristic IR spectral data for TBP and the HCl/Ni/Co/Fe-containing extracts

Fig. 7 IR spectra for HCl-loaded, nickel-loaded, cobalt-loaded, iron-loaded and untreated extractants. 4. Selective extraction and removal of Fe(III) from industrial waste Based on the above fundamental research, a test of the 2-step extraction procedure was conducted

Journal Pre-proof using an organic extractant composed of 50% (v/v) TBP and 20% (v/v) 2-octanol in kerosene and a feed containing 26.13 g/L Fe3+, 57.08 g/L Co2+, 180 g/L Cl- and 1 mol/L H+ at an O/A ratio of 2 for 5 min. The changes in the composition after extraction are shown in Table 2 and the flowchart is shown in Fig. 8. As shown in Table 2, the extraction of iron reached 99.6% after the first step of the extraction process; almost no loss of Co(II) was observed, and the concentration was slightly increased because of the change in the volume of raffinate-1. Raffinate-1 was concentrated by evaporation to increase the concentration of residual chloride ions in the solution to remove as much iron as possible. The concentration of iron in raffinate-2 decreased from 220 mg/L to 34 mg/L after the second step of the extraction process, with a Fe/Co mass ratio greater than 3.5×10-4, which met the requirement for product preparation. The next batch of fresh liquid was subjected to one extraction using the previous

of

batch of secondary extractant to displace the cobalt present in the organic phase. The loaded organic phase can be easily stripped and regenerated using deionized water in two stages. This process is

ro

simple to implement, achieving good separation of iron from cobalt. Table 2 Items

Concentration, g/L

-p

Metal concentrations and extraction Extraction %

CFe

CCo

Fe

Feed

26.13

57.08

-

Raffinate-1

0.11

58.65

Evaporation

0.22

94.83

Raffinate-2

0.034

96.33

3+

Co

Fe/Co mass ratio

2+

0.46

99.57

<1.51

1.9×10-3

-

-

2.3×10-3

>3.34

3.5×10-4

lP

re

-

84.55

Jo ur

na

P.S. The extraction of cobalt is estimated based on the basic data presented in Figs. 5 and 6.

Jo ur

na

lP

re

-p

ro

of

Journal Pre-proof

Fig. 8 Flowchart showing the extraction and separation of Fe3+ from Co2+ (feed: 26.13 g/L Fe3+, 57.08 g/L Co2+, 180 g/L Cl-, and 1 mol/L H+; organic solvent: 50% (v/v) TBP, 20% (v/v) 2-octanol, and 30% (v/v) kerosene; extraction: O/A=2; stripping: water, O/A=2) 5. Conclusions

(1) Nickel was not extracted by TBP and 2-octanol, for which the inclusion was less than 1.1%. (2) The extraction of 30 g/L cobalt increased as the concentration of hydrochloric acid increased, and the extraction exceeded 28% in the presence of 8 mol/L HCl. The complex formed between TBP and cobalt was [H3O · TBP]2 · [CoCl42-], while [H2CoCl4] · n[2-octanol] was considered an extracted form of 2-octanol and cobalt. (3) TBP was an effective extractant for the selective extraction and separation of iron from chloride-containing media. During the extraction process, the complexes formed by TBP and 2-octanol with iron were [H2FeCl4 · 2TBP] and [H2FeCl4 · 5(2-octanol)]. (4) The mass ratio of Fe/Co decreased from 0.46 in the feed containing 26.13 g/L Fe3+ and 57.08 g/L Co2+ to 3.5×10-4 in raffinate-2 after the two-step extraction process. The loaded organic phase can be stripped completely and regenerated in two stages using deionized water.

Journal Pre-proof

References Bao, Y., Shao, L., Xing, G. and Qi, C., 2019. Cobalt, nickel and iron embedded chitosan microparticles as efficient and reusable catalysts for Heck cross-coupling reactions. International Journal of Biological Macromolecules, 130: 203-212. Cárdenas-Triviño, G. et al., 2017. Chitosan doped with nanoparticles of copper, nickel and cobalt. International Journal of Biological Macromolecules, 104: 498-507. Fernandes, A., Afonso, J.C. and Dutra, A.J.B., 2013. Separation of nickel(II), cobalt(II) and lanthanides from spent Ni-MH batteries by hydrochloric acid leaching, solvent extraction and precipitation. Hydrometallurgy, 133: 37-43.

of

Gaikwad, A.G., 2004. Synergetic transport of europium through a contained supported liquid membrane using trioctylamine and tributyl phosphate as carriers. Talanta, 63(4): 917-926.

ro

Gaudon, M. et al., 2014. Cobalt and nickel aluminate spinels: Blue and cyan pigments. Ceramics International, 40(4): 5201-5207.

-p

Hanner, L.A., Pittari, J.J. and Swab, J.J., 2018. Dynamic hardness of cemented tungsten carbides. International Journal of Refractory Metals & HARD MATERIALS, 75: 294-298. Lee, M. and Oh, Y., 2005. Chemical Equilibria in a Mixed Solution of Nickel and Cobalt Chloride.

re

Materials Transactions, 46(1): 59-63. Transactions, 45(6): 1859-1863.

lP

Lee, M., Lee, G. and Sohn, K.Y., 2004. Solvent Extraction Equilibria of FeCl3 with TBP. Materials Li, L., Xu, S., Ju, Z. and Wu, F., 2009. Recovery of Ni, Co and rare earths from spent Ni–metal hydride batteries and preparation of spherical Ni(OH)2. Hydrometallurgy, 100(1-2): 41-46.

na

Li, M., He, Z. and Zhou, L., 2011. Removal of iron from industrial grade aluminum sulfate by primary amine extraction system. Hydrometallurgy, 106(3-4): 170-174.

Jo ur

Mishra, R.K., Rout, P.C., Sarangi, K. and Nathsarma, K.C., 2010. A comparative study on extraction of Fe(III) from chloride leach liquor using TBP, Cyanex 921 and Cyanex 923. Hydrometallurgy, 104(2): 298-303.

Orefice, M., Audoor, H., Li, Z. and Binnemans, K., 2019. Solvometallurgical route for the recovery of Sm, Co, Cu and Fe from SmCo permanent magnets. Separation and Purification Technology, 219: 281-289.

Qixiu, Z., Guiqing, Z. and Ruiren, T., 2014. Fundamentals and practice of solvent extraction in hydrometallurgy. Changsha：Central South University Press, 78 pp. Reddy, B.R. and Sarma, P.V.R.B., 1996. Extraction of iron(III) at macro-level concentrations using TBP, MIBK and their mixtures. Hydrometallurgy, 43: 299-306. Ribeiro, P.P.M. et al., 2019. Nickel carriers in laterite ores and their influence on the mechanism of nickel extraction by sulfation-roasting-leaching process. Minerals Engineering, 131: 90-97. Rongsun, Z., Zhuqing, G. and Hanying, J., 1983. A study of the chloride and sulfate complexs of nickel. Journal of Central South Institute of Mining and Metallurgy(8): 118-125. Saji, J. and Reddy, M.L.P., 2001. Liquid–liquid extraction separation of iron(III) from titania wastes using TBP–MIBK mixed solvent system. Hydrometallurgy, 61(2): 81-87. Sarangi, K. et al., 2007. Separation of iron(III), copper(II) and zinc(II) from a mixed sulphate/chloride

Journal Pre-proof solution using TBP, LIX 84I and Cyanex 923. Separation and Purification Technology, 55(1): 44-49. Sarangi, K., Padhan, E., Sarma, P.V.R.B., Park, K.H. and Das, R.P., 2006. Removal/recovery of hydrochloric acid using Alamine 336, Aliquat 336, TBP and Cyanex 923. Hydrometallurgy, 84(3-4): 125-129. SHEN, Y., XUE, W. and NIU, W., 2008. Recovery of Co(II) and Ni(II) from hydrochloric acid solution of alloy scrap. Transactions of Nonferrous Metals Society of China, 18(5): 1262-1268. Sun, X., Sun, Y. and Yu, J., 2016. Removal of ferric ions from aluminum solutions by solvent extraction, part I: Iron removal. Separation and Purification Technology, 159: 18-22. Wang, X., Liu, W., Liang, B., Lü, L. and Li, C., 2016. Combined oxidation and 2-octanol extraction of iron from a synthetic ilmenite hydrochloric acid leachate. Separation and Purification Technology, 158: 96-102.

of

Yu, S. and Chen, J., 1989. Stripping of Fe(III) Extracted by Di-2-ethylhexyl Phosphoric Acid from Sulfate Solutions with Sulfuric Acid., 22: 267-272.

ro

Zhai, X. et al., 2010. Leaching of nickel laterite ore assisted by microwave technique. Transactions of Nonferrous Metals Society of China, 20: 77-81

-p

.

Zhou, X. et al., 2019. Recovery of Ga(III) from chloride solutions by solvent extraction with Cextrant

Jo ur

na

lP

re

230. Hydrometallurgy, 185: 76-81.