Extraction of Boron and Vanadium from Abu Hamata Alkali Leach Solution by using Ion Exchange Resin

Extraction of Boron and Vanadium from Abu Hamata Alkali Leach Solution by using Ion Exchange Resin

Abdellah, W.M., Amer, T. E., Abdel Wahab, G. M., AlShami, A. S.

Nuclear Materials Authority, P.O Box 530, El-Maadi, Cairo, Egypt.

El-Shahat, M.F.

Ain Shams University, Faculty of Science, Chemistry Department, Cairo, Egypt.

Abstract– This work is concerned with the recovery of boron and vanadium from an ore residue originally collected from Abu Hamata mineralized sandy claystone ore material. The latter was previously treated to selectively extract its uranium and lanthanides contents through applying H2SO4 acid agitation leaching step. These two metal values which were left behind in the spent residue was found to assay 0.123 and 0.186 % for boron and vanadium respectively. The present work involves alkali roasting of the spent residue with NaOH at the obtained optimum roasting conditions. This was followed by water leaching of the roasted matrix to bring out the dissolved boron and vanadium. The latter's were then extracted via Amberlite IRA743 anion exchange resin. Pure products of H3BO3 acid and V2O5 were obtained. A tentative technical flowsheet was proposed and described.

Keywords: Extraction, Boric acid, Vanadium oxide, Ion exchange resins, Abu Hamata sandy claystone

1. INTRODUCTION

   Abu Hamata sandy claystone rock facies of Um Bogma Formation, which occurs at Abu Zeneima area, Southwestern Sinai, Egypt, is considered as one of the most important occurrences of U mineralization beside the associated economic metal values e.g. Ln, B, V, Zn, Cu,. etc [1]. Either uranium and lanthanides or boron and vanadium were found in relatively reasonable grades, 0.183, 0.137, 0.11 and

   o.175 % respectively. It is worthy to mentioned herein that, the authors have studied in detail the mineralogical and chemical composition of the raw ore material as well as the optimum conditions for selective recovery of uranium and lanthanides through applying H2SO4 acid agitation leaching process. These conditions involved 5% H2SO4 acid concentration, S/L mixing ratio of 1/2, leaching time of 1h and leaching temperature of 750C. In addition, The obtained results from the mineralogical study revealed that the study ore material consists mainly of montmorillonite as the main clay mineral (K,Ca)Al2SiO4 together with quartiz (SiO2), hematite (Fe2O3) and the secondary uranium mineral renardite Pb(UO2)2(PO4)2.8H2O]. On the other hand, the study ore material shows no specific minerals for either lanthanides, boron or vanadium. This is probably due to their adsorption upon clay mineral of the study ore material.

   With respect to boron and vanadium recovery studies, several authors have been studied the recovery of both boron and vanadium from their leach liquors via anion exchange resins [2-9].

   In this context, the ore material left after uranium and lanthanides can be probably processed for the dissolution and recovery of the other contained metal values namely; boron and vanadium. The latter would be greatly facilitated after U and Ln recovery. However, the present work aims to prepare pure H3BO3 and V2O5.

2. EXPERIMENTAL

   A .Materials

   The bead-type ion exchange resin, Amberlite IRA743 (Rohman and Hass ion exchange resins) is a macroporous styrenic resin with methyl glucamine functionality. It is commonly known that boron and vanadium are retained, borate and vanadate ions are complexed by two sorbitol groups, and a proton is retained by a tertiary amine site, which behaves as a weakly basic anion exchanger. The characteristics of Amberlite IRA743 are listed in table (1). The chemicals used during the experiments and analysis were reagent-grade Merck products.

   Table(1): Characteristics of ion exchange resin Amberlite IRA743

   Parameter	Amberlite IRA743
   Matrix Functional group Physical form Ionic form as shipped Total capacity Moisture holding capacity Shipping weight Particle size Harmonic mean size Uniformity coefficient < 0.300 mm	Macroporous polystyrene N-Methylglucamine Beige-coloured beads Free Base (FB) 0.8eq/L 48 to 54 % (FB form) 700 g/L (43.7 lbs/ft3) 0.500 0.700 mm 1.6 1 % max

   1. Alkali roasting of the ore residue

      The alkali roasting process was conducted by mixing solid NaOH with the spent residue at slightly high temperature for different periods of times. After that the cooled roasted matrix was then undergoes water leaching to dissolve its boron and vanadium contents. All the experimental roasting procedures were conducted by using constant weight (10g) of the dried ore residue. While boron and vanadium in all the alkaline solutions were analyzed by using the Flame Atomic Absorption Spectrophotometer (FAAS), Unicam 969, England at their proper wave lengths.

   2. Extraction of boron and vanadium from the alkaline leach liquor

   In the present work, trials to recover boron selectively from accompanying vanadium in the pre-processed ore material under consideration have been performed during extraction process. In this respect, alkali roasting process was first accomplished upon 200 g of the ore residue by using pellets of NaOH in a sample/ reagent (S/R) weight ratio of

   alkaline roasting parameters such as: sample/NaOH mixed weight ratios, roasting time and roasting temperature were studied. The expected reactions of the alkaline leaching process were illustrated in the following equations:

   2 4 2 7 2

   B2O3+8NaOH 2Na B(OH)4+H2O+ (1) 2VO + +4NaOH Na V O + H O + H+ (2) V2O5 + 2 NaOH 2 NaVO3 + H2O (3)

   1/1 at roasting temperature of 140 oC for 1.5 h. The roasted

   2

   matrix was then left to cool and leached with distilled water

   VO +

   +3NaOH Na3VO4 +H2O + H+

   (4)

   for 0.5 h at room temperature to bring out the dissolved boron and vanadium metal values.

   On the other hand, with respect to boron and vanadium recovery, the prepared alkaline solution (pH 12) was firstly treated with drops of conc. H2SO4 to precipitate its content of the interfering SiO2 from one hand, and to adjust its pH value to pH 8.5 which is very suitable for loading of boron and vanadium, from the other hand. Moreover, the precipitate of Si-gel should be washed with 1% H2SO4 solution to bring out any loaded boron or vanadium again to the alkaline solution. After filtration, the filtrate and the washing solution were closed up to volume of 2L. The latter was then directed to the ion exchange unit which consists of a column of 100cm in height and 0.7cm in diameter packed with 65ml of wet settled resin (wsr) Amberlite IRA743 in its hydroxide form. The applied flow rate was 2.5 ml/min. The collected effluent solutions of 100ml bed volumes was analyzed for both boron and vanadium and their extraction efficiencies were calculated.

   The saturated loaded resin was subjected to the elution process to regenerate both of the loaded boron and vanadium. The former was firstly regenerated by using 400 ml of hot distilled H2O at a working flow rate of 1ml/min while the latter was then regenerated by using 100 ml of 4% H2SO4 at an applied flow rate of 1.5 ml/min. Fractions of 40ml bed volumes were collected and its boron content was estimated to determine the relative elution efficiency of boron. With respect to vanadium, 10 ml bed volume fractions were collected to estimate vanadium elution efficiency. The eluate rich boron was subjected to evaporation to prepare pure H3BO3 while pure V2O5 as precipitated from vanadium rich eluate solution at pH value 2.5.

3. RESULTS & DISCUSSION

As mentioned previously, the present feed sample is an ore residue originally collected from Abu Hamata sandy claystone ore material. The latter was previously treated to selectively extract uranium and lanthanides through applying H2SO4 agitation leaching step. This ore residue was thus upgraded and found to assay 0.123% B and 0.186% V. However, due to the vital importance of both boron and vanadium, it was decided to study their recovery by using anion exchange resin Amberlite IRA743 from the obtained alkali leach liquor of the study ore residue.

1. Alkali roasting of the ore residue

   The spent ore residue was firstly prepared for chemical analysis to recalculated its content of the upgraded boron and vanadium metal values after removing uranium and lanthanides together with other deleterious constituents e.g. Mg, Ca, Na, K,etc. From the latter, boron was found to assay 0.123% while vanadium assaying 0.186%. Several

   1. Effect of ore residue / NaOH weight ratios (S/ R):

      The effect of ore residue /NaOH weight ratios upon the dissolution efficiencies of boron and vanadium were studied by mixing different ratios in the range between 4/1 to 1/2. The mixed material was roasted in a porcelain crucible at 140 0C for 1 h. The roasted matrix was left to cool and then subjected to water leaching for 0.5 h at room temperature. After filtration and washing the total volume was closed to 100 ml. Both of boron and vanadium were determined and their dissolution efficiencies were calculated.

      The obtained data table (2) emphasized that the dissolution efficiencies of the metals of interest increased with decreasing the ore /NaOH ratio from 4/1 to 1/1, where for boron it is increased from 57 to 89.4% and for vanadium it is increased from 51.2 to 90.1%. The ore/NaOH ratio less than 1/1 decreases the dissolution efficiency of boron while increasing that of vanadium. Therefore, the mixed ratio of 1/1 was found to be suitable for applying the other roasting parameters.

      Table (2): Effect of Ore/NaOH weight ratio upon dissolution efficiencies of boron and vanadium.

      Ore/NaOH Wt. ratio	Dissolution efficiency (%)
      	B	V
      4/1	57.0	51.2
      3/1	59.4	61.7
      2/1	87.9	70.8
      1/1	89.2	90.1
      1/2	75.0	94.0

   2. Effect of roasting temperature

      The effect of roasting temperature upon the dissolution efficiencies of both boron and vanadium was studied in the temperature range from 90 to 300 0C. The applied ore/NaOH weight ratio was kept at 1/1 and 1h as roasting time. Data in table (3) shows that, by increasing the roasting temperature from 90 to 1400C the dissolution efficiencies of boron and vanadium show a significant improvement. However, with respect to boron the dissolution efficiency increased to its maximum value of 89.2% at 1400C. Further increase in roasting temperature to 300 0C shows an opposite effect. This might be due to the formation of insoluble borosilicate compounds at high temperature which might be complicate the subsequent recovery [10]. This emphasized the association of boron with clay minerals. On the other hand, with respect to vanadium, it is almost dissolute at 200 0C while at the temperature of 170 oC it is slightly improved to 94.6%. Therefore, the roasting temperature at 140 0C would represent the optimum one for dissolution of both boron and vanadium.

      Table (3): Effect of roasting temperature upon the dissolution efficiencies of boron and vanadium.

      Temperature (oC)	Dissolution efficiency (%)
      	B	V
      90	27	78.5
      140	89.2	90.1
      170	85.6	94.6
      200	79.8	100
      300	45.7	100

   3. Effect of roasting time

      The effect of roasting time upon the dissolution efficiencies of boron and vanadium from the study ore residue was studied in the range between 0.5h to 3h. The other roasting factors were fixed at roasting temperature of 140 0C and ore/NaOH weight ratio of 1/1. The obtained data represented in table (4) emphasized that, the roasting time of 1.5h can be considered as the more suitable to attain satisfactory dissolution efficiencies for both of boron and vanadium which achieved 94.1 and 97% respectively.

      Time (h)	Dissolution efficiency (%)
      	B	V
      0.5	71.2	85.0
      1	89.2	90.1
      1.5	94.1	97.0
      2	94.5	98.4
      3	90.1	95.1

      Table (4):Effect of roasting time upon the dissolution efficiencies of boron and vanadium. .

      Fig.1. A scheme of building chemical structure of Amberlite IRA743

      3

      4

      In the alkaline solution, both of boron and vanadium were found in the anion species borates [B(OH)4]- and vanadates (VO3) at pH value over 8 [6]. The process of extraction depends upon the substitution reaction between the borate [B(OH)4]-, vanadates (VO ) anions and anionic resin sites. Figs. (2, 3) describe the mechanism of the uptake of both boron and vanadium from the aqueous solutions. The uptake of boron as borate anion B (OH) – and vanadium as vanadates anion (VO3)- is a curious mechanism, where it involves protonation of the amine, de-protonation of the ploy sugar tail. Boric acid dissociate in distilled H2O to form the borate anion. While the protonation process of the amino group will be taken place as illustrated in equations below.

      4

      B(OH)3 B(OH) – + H+ (5)

      -CH2-N- CH2-CH2- + H+ -CH2-N+ H- CH2-CH2- (6)

      In the light of the foregoing mentioned alkali roasting process of Abu Hamata ore residue, it can be concluded that, the optimum roasting conditions required for dissolving 94.1% of boron and 97 % of vanadium are as following:

      Ore/NaOH wt. ratio : 1/1 Roasting time : 1.5 h Roasting temperature : 140 0C

      These determined optimal roasting conditions are used to prepare the pregnant leach liquor for subsequent recovery of both boron and vanadium. Accordingly, 200 g of the ore residue was used to yield 2 liters of alkaline leach liquor. The latter was found to assay 0.116 g/l of B, 0.18 g/l of V, 10.2 g/l of Si and pH value of 12 .

2. Extraction of boron and vanadium from the alkaline leach liquor

   In this context, Amberlite IRA743 anion exchange resin was used. The latter has a macro porous poly-styrene matrix, on which N-methyl glutamine functional groups (R-N(CH3)- C6H8(OH)5) are attached as represented by Fig. (1).

   Fig. 2. A scheme of boron uptake mechanism from the aqueous solutions.

   3

   With respect to vanadium uptake upon the resin sites, VO – species has been adsorbed through electrostatic attraction and complexed with N+ and OH groups of the resin sites.

   Fig. 3. A scheme of vanadium uptake mechanism from the aqueous solutions.

   1. Si-gel precipitation before Loading of boron and vanadium

      Before applying the loading process of boron and vanadium upon the resin, it is important to remove silica gel as by-prodct from the prepared alkaline leach liquor. The purpose is to avoid coating of the exchange sites of the resin. This was carried out by adjusting the pH value of the prepared alkali leach liquor via conc. H2SO4 to be 8.5. The precipitated silica in the form of SiO2-gel should be washed with dilute H2SO4 (1%) during filtration to avoid the loss of any dissolved boron and vanadium by adsorption on its outer surface. The precipitate of SiO2-gel was then ignited at 850ºC for 1h and left to cool and then washed. After dryness, SiO2 was recovered with recovery efficiency up to 99%. The produced

      SiO2 was identified by means of XRD technique as shown in Fig. (4).

      Fig. 4. XRD pattern for the identification of the produced SiO2.

      It is important to mentioned herein that, the chosen pH value of 8.5 represent the optimum value for uptake of both boron and vanadium [3, 11-12]. At pH values higher than 9, boron extraction efficiency decreased because an amount of other interfering species especially the excess (OH)- could be retained by resin [13]. Also, at pH values below 7, H3BO3 is the dominant species which has a low extraction efficiency due to low electrical activity [14].

   2. Loading process of both boron and vanadium

      In the present work, 2 Liters of the prepared leach liquor was passed through the resin column packed with 65 ml wsr at a working flow rate of 2.5 ml/min. The obtained effluents were collected every 100 ml for boron and vanadium analyses. From the obtained results (Fig.5), it is evident that, the amount of loaded boron upon the resin was 0.203g realizing high loading efficiency of 87.5%. While the amount of the loaded vanadium was 0.255g with the loading efficiency of 70.46%. The calculated capacity of the working resin for both of both boron and vanadium represented about 79%. This relatively low capacities may be due to the competition of some anions in the resin sites especially OH – ions. Finally, the saturated resin was rapidly washed with distillated H2O to remove the remains of loaded ions before applying the elution process.

      Fig. 5. loading curve of both boron and vanadium from the treated alkaline solution.

   3. Elution process of the loaded boron and vanadium

      Elution process is not only used to regenerate the loaded resin but also to prepared a concentrated solutions suitable for the subsequent precipitation process to prepare the final element products. Different elute solutions suggest good elution efficiencies for both of boron and vanadium e.g. dilute HCl, H2SO4 and NaOH. However, any of these eluants can be used for the elution of the loaded elements of interest.

      In the present work, to avoid the problem of interfering the two elements of interest during elution, the loaded Amberlite IRA743 was firstly subjected to selective elution process of boron by using hot H2O to regenerate B(OH)4 anion species depending upon the high solubility of borate ions in distilled water [15]. This was followed by vanadium elution by using 4% H2SO4 acid.

      1. Elution of boron and preparation of pure boric acid (H3BO3)

         Accordingly, the loaded resin when treated with hot H2O or very weak acid solution is being regenerated to its original structure (Fig. 6), as illustrated by the following:

         Hot H2O

         + H3BO3

         Fig. 6. A scheme of boron elution mechanism from the loaded resin

         For this purpose, suitable volume of 400ml hot H2O was used at working flow rate of 1m/min to regenerate almost loaded boron (95.3%). The eluate solution fractions each of 40ml bed volumes were collected to determine their boron content and to calculate the corresponding elution efficiency as plotted in Fig.(7).

         Fig. 7. Elution curve of boron from the loaded Amberlite IRA743

         The recovery of boron in the form of boric acid as pure crystals from boron eluate concentrated solution seems possible by partial evaporation. About 400 ml of the eluate solution contains 0.193 g boron was used for the preparation of 1.08 g boric acid (H3BO3). The obtained product has purity reached about 96.9% together with some trace of NaCl and V.

         For further purification, the product was re-dissolved in distilled H2O and then directed to the anion exchange unit. After loading and elution processes, the eluate rich boron solution was re-crystallized by evaporation to produce high pure H3BO3 acid as shown in Fig.(8).

         Fig. 8. XRD pattern of pure boric acid (H3BO3).

      2. Elution process of vanadium and preparation of pure red

Fig. 10. Elution curve of vanadium from the loaded Amberlite IRA 743.

3

The eluate sulfate solution which assays 2.4 g/l of vanadium was used to prepare the final vanadium product. However, 100ml of vanadium rich solution was adjusted to pH 2.5 with NH4OH solution and then oxidized by the addition of 0.25g KClO3. Complete precipitation of vanadium (98.2%) as a red cake (V2O5) was obtained at 75 0C after 2h stirring time. The product was then filtrate and washed with distilled water to remove the associated salts. The obtained red cake was then dried in the oven at 120 0C for a suitable period of time. The latter was identified by means of EDX analysis as shown in Fig. (11). The chemical analysis proved that the purity of the final product (V2O5)was 95.9%.

cake (V2O5)

After eluting of almost boron content from the loaded Amberlite IRA743 anion exchange resin, vanadium elution process takes place. For this purpose 100 ml of 4%H2SO4 acid solution at flow rate of 1.5 ml/min was used. Fig. (9) shows the expected mechanism elution from the loaded Amberlite IRA743 anion exchange resin.

2VO –

(aq.)

+

+ 2H

(aq.)

V2O

5 (s)

+ H2O (7)

4% H2SO4

+ VO2+ + SO42-

Fig. 9. A scheme of vanadium elution mechanism from the loaded resin.

The eluate solutions each of 10ml bed volumes were collected to determine their vanadium content. From the latter, it was found that, vanadium was eluted with elution efficiency of 96.8%.The corresponding elution results were plotted in Fig. (10).

Fig. 11. EDX chart for the identification of pure red cake,(V2O5).

1. CONCLUSION

   From the forgoing study, the following general conclusion can be summarized:

   1. A procedure for separating the loaded boron from the accompanying vanadium upon Amberlite IRA743 anion exchange resin can be achieved by using hot H2O as an eluant for boron and 4 % H2SO4 acid for vanadium.

   2. A procedure to prepare pure Si-gel as by-product was achieved by adjusting pH of the pregnant alkali solution to

      8.5. The latter was found to be the suitable pH for boron and vanadium loading upon the Amberlite IRA743 resin.

   3. Finally, a proposal technical flowsheet for processing Abu Hamata ore residue to obtain pure H3BO3 and V2O5 was designed Fig.(12).

2. REFERENCES

[1]. AlShami, A.S., "Structural and Lithologic controls of uranium and copper mineralization of Um Bogma Evirons , Southwestern Sinai, Egypt.", Ph.D. Thesis, Geology Department, Faculty of Science, Mansora University, 2003.

[2]. Mahmoud, A.H., "Study on some Egyptian resources of V and its extraction from these resources", Ph.D. Thesis, Faculty of Science, Helwan University, 2004.

[3]. Ozdemir, M. and Kpcak, I., "Boron Recovery from Borax Sludge Using SolidLiquid Extraction Followed by Sorption with a Boron Selective Resin in Column", Environmental Progress, Vol. 26, No.4, pp. 375-383, 2007.

[4]. Hu, J., Song, S.G. and Zhang, B.Q,"Removal of vanadium from molybdnate solution by ion exchange", Hydrometallurgy, Vol.95, pp. 203206, 2009.

[5]. Zeng, L., Li, Q.G. and Xiao, L.S., "Extraction of vanadium from the leach solution of stone coal using ion exchange resin", Hydrometallurgy, Vol.97, pp.194197, 2009.

[6]. Wang, X., Wang, M., Shi, L., Hug, J. and Qiao, P.,"Recovery of vanadium during ammoniu molybdate production using ion exchange", Hydrometallurgy, Vol.104, pp.317321, 2010.

[7]. Ming-yu, W. , Xue-wen, W. , Ji-feng, S. and Ri-na, W.,"Extraction of vanadium from stone coal by modified salt-roasting process, J. Central South University of Technology, Vol.18, No.6, pp. 1940-1944, 2011.

[8]. Abdel Wahab, G. M.," Recovery of boron from the borosilicate tourmaline mineral of Sikait area, Eastern Desert, Egypt, Egyptian Journal of analytical Chemistry, Vol. 21, pp. 1-14, 2012.

[9]. Abou El- Enein, S., Abdel Wahab, G., Mira, H. and RaShad, M.," Recovery of Boron from the Waste Slag of Steel Factories by using Selective Ion Exchange Resin, International Journal of Engineering Research & Technology, Vol. 2, No.11, pp. 1255-1263, 2013.

[10]. Vick, G. L. and Whittle, K. M.,"Solid Solubility and Diffusion Coefficients of Boron in Silicon, Electro chememical Soc., Vol. 116, No.8, pp.1142-1144,1969.

[11]. Ki-Won, B., Sang-Hun, S., Seok-Hwan, K., Young-Woo, R., Chang- Soo, L., Bum-Jae, L., Sam, H. and Taek-Sung, H., "Adsorption Kinetics of Boron by Anion Exchange Resin in Packed Column Bed'', J. Ind. Eng.

Chem., Vol. 13, No.3, pp. 452-456, 2007

[12]. Jin-Wen, H., Peng, S., Wen-Wei W., Sen L.;Hui-Quan, Q. , Xue-Hang W., Xiao-Hu H.;Liu-Jia T. and Yan-Jin, F. ,"Concentration and separation of vanadium from alkaline media by strong alkaline anion-exchange resin 717", Rare Metals, Vol. 29, No. 5, pp. 439-443,

2010.

[13]. Muetterties, E.L., The chemistry of boron and its compounds, 1967, New York: Wiley.

[14]. Del Mar de la fuente Garcia-Soto, M., "Eugenio Munoz Camacho , Boron removal by means of adsorption with magnesium oxide", Separation and purification Technology, Vol. 48, pp. 36-44, 2006.

[15]. Lahoda, E.G., Battagli, J. A. and Impink, A.J., "Boron isotopes separation by anion exchange chromatography", USA Patent No.5,44,732, August 22, 1995.