Anal. Methods Environ. Chem. J. 4 (4) (2021) 64-77
Research Article, Issue 4
Analytical Methods in Environmental Chemistry Journal
Journal home page: www.amecj.com/ir
AMECJ
Recovery of Vanadium by ammonium chloride precipitation
method using response surface methodology
Mahshid Gharagozloua, Hossein Sid Kalalb,*, Alireza Khanchi b,
Sohrab Ali Ghorbaniana, Seyed Ebrahim Mosavia, Mohammad Reza Almasianb,
Danial Niknafsc, Akram Pourmatinb, Neda Akbarib
a Department of Chemical Engineering, Faculty of Engineering, University of Tehran, Tehran, Iran.
b Nuclear Fuel Research School, Nuclear Science and Technology Research Institute, AEOI, P.O. Box 3486-11365, Tehran, Iran.
c Department of Chemistry, Mashhad Branch, Islamic Azad University, Mashhad, Iran.
ABSTRACT
In this study, vanadium recovers from an alkaline solution based on
the precipitation process and response surface methodology. A white
salt ammonium metavanadate was obtained using the ammonium
chloride precipitation method. Ammonium chloride was added
directly to the alkaline liquor solution and the pH was adjusted
approximately between 5 and 7 to form the white salt. The parameters
affecting the recovery of vanadium, including the ammonium chloride
concentration, the pH and the vanadium concentration in the caustic
solution, were examined. The precipitation time had no signicant
inuence on the vanadium recovery. The concentration of vanadium
in the caustic solution and the concentration of ammonium chloride
used for the precipitation were inversely related. It was found that a
high recovery (over 90%) can be achieved with ammonium chloride
and vanadium with concentrations over 4% (w/v) or 1000 mg L-1 (in
the lye solution). It has also been observed that working in the pH
range of 5 to 7 results in over 90% recovery. The inuence of the
parameters mentioned on the recovery of impurities was examined and
the optimal values determined. Ultimately, the maximum vanadium
recovery (97.29%) was achieved at the optimal point obtained from
the reaction surface methodology.
Keywords:
Vanadium,
Recovery,
Ammonium chloride precipitation,
Alkaline leach solution
ARTICLE INFO:
Received 6 Aug 2021
Revised form 27 Oct 2021
Accepted 25 Nov 2021
Available online 29 Dec 2021
*Corresponding Author: Hossein Sid Kalal
Email: hsidkalal@aeoi.org.ir
https://doi.org/10.24200/amecj.v4.i04.153
------------------------
1. Introduction
Vanadium is of industrial and strategic importance
due to its particular use. The main application
of this element is in the steel industry. The
highest production of vanadium in the world is
in the form of vanadium pentoxide. Vanadium
and its compounds are widely employed in the
metallurgical, petrochemical, defense, electronics
and paint and coating industries due to their
excellent mechanical, catalytic, magnetic and other
physicochemical properties. The primary sources
of vanadium compounds are ore feedstocks,
concentrates, metallurgical slags, and petroleum
residues [1,2]. Different methods have been applied
for vanadium precipitation depending on leach
solution (acidic, alkaline, or aqueous solutions).
The followings are the studies and methods used
to precipitate vanadium from these three leach
solutions. Vanadium can be recovered from a leach
solution by adjusting the pH with sulfuric acid
or hydrochloric acid and adding an ammonium
salt at temperatures between 22 and 28 °C [3].
Sodium hexavanadate Na4V6O17 (red cake) can be
65
precipitated by adding sulfuric acid with a pH of
2-3, and the precipitate is dissolved in an aqueous
sodium carbonate solution. The red cake is cleaned
and some impurities such as iron, aluminum, and
silicon are separated from the solution by pH
adjustment and precipitation. Then, ammonium
chloride is added to the ammonium metavanadate
precipitate. The calcination step is carried out, and
vanadium pentoxide (V2O5) is nally obtained
with a purity of 99.8% [4]. There is a relationship
between the temperature of ammonium addition
and the Precipitation Rate (PR), with the PR
being 99.5% from 30 to 65°C while the PR
decreases at temperatures below 35°C because the
solubility of ammonium sulfate is not the same
at different temperatures and dissolves faster at
high temperatures. The presence of pollutants
also affects the precipitation process. The sodium
concentration inuences the precipitation process,
as sodium ions replace NH4
+ ions. High sodium
contents prevent the replacement of Na+ by NH4
+.
Therefore the amount should be controlled and
below 25 g L-1. The silicon concentration should
be below 1.5 g L-1. A high aluminum concentration
prevents the formation of ammonium polyvanadate
crystals, so the concentration should be below
0.1 g L-1 [5]. In another study, the technology for
extracting vanadium from coal was investigated.
Scholars were able to precipitate ammonium
metavanadate by leaching (with water) and adding
acid (sulfuric acid or hydrochloric acid) to form
polyvanadate. The precipitate was dissolved with
sodium hydroxide, and ammonium salt was added.
Then, calcination process was performed at 550 °C.
Finally, vanadium pentoxide was obtained [6, 7].
Based on research by Wang et al., they worked
on an alkaline sodium hydroxide leach solution
containing 84.45 gL-1 vanadium pentoxide.
Ammonium metavanadate was precipitated by
adjusting the pH with hydrochloric acid in the range
of 8 to 8.5. Ammonium chloride was added at 40 - 45
°C. Then, vanadium pentoxide was obtained with a
purity of 99.12% by calcination at 550 °C for one
hour [8]. Iron and nickel do not enter the solution
in alkaline leaching with sodium hydroxide, but
aluminum and silicon enter the solution with
vanadium. During acid leaching, sulfuric acid,
iron, nickel, aluminum, and silicon enter the
solution with vanadium. In leaching with sodium
carbonate, only aluminum is introduced, and other
metals do not get into the solution with vanadium.
In the alkaline leaching process, sodium hydroxide
was precipitated by adjusting the pH to 8 with
sulfuric acid in the absence of ammonium chloride,
aluminum, and silicon, while vanadium was in the
solution. The addition of 1-2 M ammonium chloride
solution and adjustment of the pH to 5 was resulted
in the formation of a vanadium precipitate [9]. The
technology of vanadium extraction from coal was
also developed in another study. The focus was
on cleaning the alkaline leach solution to remove
silicon and aluminum. This purication took place
in two stages. In the rst stage, most of the sulfuric
acid impurities were removed by adjusting the
pH in the range of 8 to 9. In the second stage, the
remaining silicon, aluminum, and other impurities
such as phosphorus were removed by chemical
precipitation. The chemical precipitation was
obtained by adding 8 g L-1 magnesium nitrate and
10 ml L-1 ammonia at 60°C for 1 hour in a shaker
with a speed of 500 rpm. The vanadium recovery in
this process was 94.25% [10]. In another study, the
focus was on vanadium recovery from consumer
catalysts. Acid leaching and precipitation were
performed by adjusting the pH to 6 – 7 with 1
M sodium carbonate solution. It was found that
precipitation at pH levels above 7 should be avoided
as this will lead to the precipitation of nickel and
other metals [11]. The precipitation of vanadium
can be achieved by adding ammonium chloride
and an alkali such as sodium hydroxide to an acidic
leach solution to adjust the pH. The solubility
of sodium metavanadate increases with the pH
value of the alkaline solution and temperature.
Vanadium pentoxide was obtained with a purity of
99% [12]. In the recovery of vanadium from the
acidic leach solution of charcoal, scholars could
obtain vanadium pentoxide with a purity of 99%.
Ammonium chloride was added to a solution at a
pH of about 2, and the precipitate of ammonium
Response Surface Methodology for Recovery of Vanadium Mahshid Gharagozlou et al
66
vanadate was taken out. The precipitate was roasted
at 520 °C for 2 hours, and vanadium pentoxide was
obtained with a purity of 99% [13]. The recovery
of molybdenum and vanadium from consumable
catalysts was investigated. Ammonium chloride
is widely used for vanadium precipitation in the
industry because of its economic cost. An excessive
amount of ammonium chloride is required because
excess ammonium chloride causes vanadium
precipitation and ammonium solubility. As a result,
the solubility of ammonium vanadate in the solution
decreases as the ammonium chloride concentration
increases. More than 99% of vanadium precipitates
if the concentration of vanadium pentoxide in
the solution is 25 g L-1, and the concentration of
ammonium chloride is more than 40 g L-1. It was
found that the concentrations of vanadium pentoxide
in the leach solution and ammonium chloride are
heavily involved in the vanadium precipitation
process and are interdependent. It is also stated that
the precipitation reaction takes place at pH range
of 8 to 9 [14,15]. Based on studies carried out and
considering that the Saghand ore is of the titanium
magnetite type and the amount of vanadium in the
ore is about 5000 mg L-1, the suitable method for
vanadium recovery from this ore type is salt roasting
with sodium carbonate and leaching with hot water.
The leach solution used in our study has been
prepared under the same conditions, ie salt roasting
and leaching with hot water, and the precipitation
process has been performed in the alkaline solution
obtained by leaching with hot water. The reason for
choosing the precipitation method is its low cost
and simplicity of the process. Therefore, such a
process is of great importance for large-scale use
due to industrial needs and constraints. A thorough
review of similar studies revealed that complete and
accurate information about the optimal conditions
for vanadium precipitation is not available. In this
study, preliminary experiments were performed
to determine the optimal precipitation conditions.
The important parameters including ammonium
chloride concentration, pH, precipitation time and
vanadium concentration in the leach solution were
investigated and their optimal values were specied
2. Experimental
2.1. Materials and analytical instruments
All materials and reagents including FeCl3 (99%),
NaVO3 (98.5%), Al(NO3)3.9H2O (95%), Ca(NO3)2
(100%), Mg(NO3)2.6H2O (99%), Na2MoO4.2H2O
(99.5%), K3PO4.3H2O (99%), SiO2 (99%), NH4Cl
(99.5%), HCl (37%), H2SO4 (98%) and (NH4)2CO3
(99.9%) were provided by Merck (Germany) in
analytical grade. All solutions were made with
deionized water. Concentration of the ions in the
solutions was determined using inductively coupled
plasma (ICP) (Varian liberty 150 XL). Induction-
coupled plasma spectroscopy is a method of
emission spectroscopy in which the atomization
takes place with the aid of plasma that is generated
by an inert gas, mainly argon. This method is used
for elemental analysis (mainly cations) of most
elements.
2.2. Precipitation process
First of all, the Saghand ore was roasted with
50% by weight sodium carbonate at 900 °C for
two hours. Then, leaching was carried out with
hot water at 90 °C for three hours with a liquid
to solid ratio of 1 to 3. Impurities in the leach
solution were identied by ICP analysis (Table
1). According to the exact amount of impurities,
a simulation solution was prepared. The Saghand
ore leach solution is in an alkaline media (pH about
10) and the simulation solution was made under
the same condition. The salts listed in Table 2. and
Table 3. Were used to prepare the alkaline leach
solution. Vanadium precipitation from alkaline
leach solutions can be carried out in two methods.
In rst method, by adjusting the pH value (pH =
2), the red precipitate of ammonium polyvanadate
is formed together with some impurities. The red
precipitate is dissolved in dilute sodium carbonate
solution and impurities are removed by setting
the pH value. Then ammonium chloride is added
and the ammonium metavanadate precipitate is
formed. In second method. Ammonium chloride is
added directly to the alkaline leach solution and the
pH value is set in the range of 5 to 7 to form the
white salt called ammonium metavanadate. If the
Anal. Methods Environ. Chem. J. 4 (4) (2021) 64-77
67
Response Surface Methodology for Recovery of Vanadium Mahshid Gharagozlou et al
Table 1. Chemical composition of the vanadium-associated impurities in the leaching solution
Composition Al Ca Fe Mg Mo P Ti Na Si
Concentration,
mg L-1 10.583 3.6 0.455 1.81 32.283 0.56 0.036 1383.33 72.916
Table 2. The precipitates of sodium vanadate salts
No. pH Vanadium
Recovery (%)
Sodium (%)
in precipitation
11.028 17.50 0.660
21.368 80.83 1.486
31.544 90.65 1.134
41.876 97.64 0.451
52.045 94.43 0.515
64.566 73.47 2.619
75.023 46.98 2.619
85.540 95.17 2.579
95.850 90.11 2.714
10 6.024 95.53 2.013
11 6.040 94.52 1.371
12 6.734 98.84 0.224
Table 3. Inuence of the concentrations of vanadium in sodium vanadate salts in the presence
of NH4Cl and pH value of 5
Ammonium chloride concentration (% w/v)
10 2.5
Vanadium
concentration, mg
L-1
100 200 500 800 500 800 1000 2000 3000
Vanadium recovery
(%) 91.125 95.396 95.833 97.948 66.433 94.406 98.125 99.125 99.288
68
amount of impurities in the leach solution is low,
the second is recommended and there is no need for
a separate step to remove impurities. Therefore, we
employed the second method because the amount
of impurities in the alkaline leach solution used
in our study is low. In this study, the concentrated
ammonium chloride was added to an alkaline leach
solution. The pH was adjusted in the range of 5 – 7
with 0.5 M HCl. A white precipitate was formed,
which corresponds to the ammonium metavandate.
The resulting precipitate was then washed with
2.5% ammonium chloride solution (w/v). Finally,
the resulting precipitate dried at room temperature.
3. Results and discussion
3.1. Effect of pH
Preliminary tests were carried out to determine the
optimal pH range for the vanadium precipitation
on sodium vanadate salt. Sodium metavanadate
(NaVO3) with a purity of 98.5% and NH4Cl with
a purity of 99.8% were used in these experiments.
Besides, 0.5 M HCl (with a purity of 32% and a
density of 1.16 kg L-1) was used to adjust the pH. In
this case, 2.085 g of NaVO3 was dissolved in 252 mL
of distilled water. Then, 28 mL of 25% ammonium
chloride (w/v) was added so that its amount in
water was 2.5% (w/v). Finally, the pH was adjusted
with 0.5 M HCl. Based on the experiments’ results
(Table 2), the highest vanadium recovery occurred
at PH values close to 2 to and close to 7. Vanadium
has polyvanadate and metanvanadate structures
at pH 2 and 7, respectively. For the rest of the
experiments, the pH value was considered to be 7
for high vanadium recovery and minimum recovery
of sodium.
3.2. Effect of ammonium chloride and vanadium
concentrations
In order to investigate the inuence of ammonium
chloride concentration in sodium vanadate solution
on the vanadium recovery, a solution containing
sodium vanadate with different concentrations
in the range of 100 to 3000 mg L-1 was tested by
adding ammonium chloride salt at a pH of about
5.5. The corresponding results are shown in Table 3.
We nd from the results in Table 3. that a vanadium
recovery of 98% with a vanadium concentration
of 1000 mg L-1 can be achieved in the presence
of 2.5% ammonium chloride. At low vanadium
concentrations, 10% ammonium chloride (which is
a very high concentration) is required for a vanadium
recovery of more than 95%. Similar experiments
were carried out in simulation solution to examine
the effect of ammonium chloride concentration.
Finally, the concentration range of ammonium
chloride was determined. The experiments were
carried out under pH = 5.5, a precipitation time of 2
hours, and a 1000 mg L-1 vanadium concentration.
Figure 1a shows how an increase in the ammonium
chloride concentration affects the recovery
of vanadium. With regard to the vanadium
concentration (1000 mg L-1), it is observed that an
ammonium chloride with concentration of about
12% (w/v) must be used to achieve a recovery of
over 90%, which is economically and industrially
unprotable. These tests show that the amount of
ammonium chloride used depends on the vanadium
concentration in the leach solution. The experiments
were carried out under pH=6.35, a precipitation
time of 16 hours, and a vanadium concentration of
2100 mg L-1. In Figure 1b, the effect of increasing
the ammonium chloride concentration on the
vanadium recovery can be observed. Ammonium
chloride was added in the range of 6 to 14 %
(w/v) to the solution containing 2100 mg L-1 of
vanadium. The recovery rate of vanadium was over
95%. Increasing the concentration of ammonium
chloride leads to increased vanadium recovery.
Since Saghand ores contain about 5400 mg L-1
of vanadium, a range between 2 to 8% for the
concentration of ammonium chloride and a range
between 1400 and 2700 mg L-1 for vanadium
concentration were considered for the remaining
tests.
3.3. Effect of precipitation time
The result of time evaluation is shown in Figure
2a. These tests were carried out under pH = 6.35,
10% (w/v) ammonium chloride, different times,
and vanadium concentration of 2100 mg L-1.
Anal. Methods Environ. Chem. J. 4 (4) (2021) 64-77
69
Fig. 1. Inuence of the ammonium chloride concentration on the vanadium recovery
for a solution with vanadium concentration of 1000 mg L-1 (a) and 2100 mg L-1 (b).
Fig. 2. a) Effect of time on vanadium recovery, b) Inuence of time on the precipitation
of various ions on ammonium metavanadate
The results showed that the increase in time did
not signicantly affect vanadium recovery. The
difference in recovery rates related to precipitation
data is less than 1% with a maximum and minimum
time of 30 and 2 hours, respectively. So, it is better to
choose the shortest time for precipitation to achieve
the maximum recovery of vanadium. According to
empirical observations, by increasing precipitation
time, the amount of impurities in vanadium rises
signicantly. To prove this claim, the effect of time
on the recovery of impurities, including aluminum,
molybdenum, sodium, and silicon was investigated.
Over time, as shown in Figure 2b, this can lead
to an increase in the amount of contaminants on
ammonium metavanadate precipitate. In the case
of elements such as silicon and aluminum, the
passage of time, in contrast to molybdenum and
sodium, signicantly inuenced the increase in ion
precipitation. Our goal is to minimize the pollution
caused by ammonium metavanadate precipitation.
As described above, two hours was considered
optimal for the precipitation process.
Response Surface Methodology for Recovery of Vanadium Mahshid Gharagozlou et al
70
3.4. The simultaneous effect of important
parameters using design expert software
3.4.1.Design of experiments
The DOE (Design of Experiment) method is one of
the new statistical methods that can be used to identify
important variables that affect the product’s quality.
By Using DOE techniques, we can rst identify
the variables that will have the greatest impact on
the output. Second, the effective input variables are
determined to bring the response values closer to their
nominal value, reduce their variability, and minimize
the inuence of uncontrollable factors on the response
variable. One technique that is widely used to optimize
the input variables is response surface methodology
(RSM). Central composite designs, abbrev i ated
as CCD or Box-Wilson, are common methods for
response surface design. The CCD method is used to
design experiments. In the CCD method, each factor
has ve different levels (including three points within
limits specied for each factor and two points outside
the limits specied for each factor). CCD design is
usually done in ve stages, including -α, -1, 0, +1, + α.
About the mentioned stages, -1 and +1 are the upper
and lower levels, and -α and + α are the new limits
of the factors. Zero is also at the heart of the design.
In this experiment, the CCD experiment design was
performed using the design-expert software to obtain
the relationship between the three process variables.
For the three variables pH (X1=A), w eight-volume
percentage of the ammonium chloride concentration
(X2 = B), and vanadium concentration in the leaching
solution (X3 = C), 20 experiments were carried out
to determine the interaction of the parameters. Each
time the parameter is designed and e x ecuted by
the software by determining the optimal point. The
specications of each Central Compo s ite Design
(CCD) test and their results are sh o wn in Table 4.
The experiment design was carried o u t with three
factors in mind. The order and the range of the factors
are given in Table 4. And the precipitation time was
considered to be 2 hours.
Table 4. Design of the experiments
Std. Run Block A: pH B: NH4Cl
% w/v
C: V2O5
mg L-1
11 1 1 6.15 2.98 2100
5 2 1 5.6 4 2500
3 3 1 5.6 7 1700
6 4 1 6.7 4 2500
19 5 1 6.15 5.5 2100
12 6 1 6.15 8.02 2100
17 7 1 6.15 5.5 2100
1 8 1 5.6 4 1700
7 9 1 5.6 7 2500
4 10 1 6.7 7 1700
13 11 1 6.15 5.5 1427.28
18 12 1 6.15 5.5 2100
15 13 1 6.15 5.5 2100
10 14 1 70.7 5.5 2100
20 15 1 6.15 5.5 2100
2 16 1 6.7 4 1700
9 17 1 5.23 5.5 2100
16 18 1 6.15 5.5 2100
14 19 1 6.15 5.5 2772.72
8 20 1 6.7 7 2500
Anal. Methods Environ. Chem. J. 4 (4) (2021) 64-77
71
3.4.2.Analysis of results
As shown in Figure 3a, pH changes have no
signicant effect on the increase or decrease
in vanadium recovery. The recovery rate was
almost high in the pH range under study. The
low vanadium recovery was due to the low
concentration of ammonium chloride. The pH
values in the range of 5 to 7, with which the
white precipitate of ammonium metavanadate
is to be captured, can achieve high recovery of
vanadium. So, the selection of all pH values in
this range is acceptable. As shown in Figure 3b,
the effect of pH on increasing vanadium recovery
is not signicant in this range. It has a maximum
recovery for vanadium at pH=6.15 with an
ammonium chloride (NH4Cl) concentration of
7% (w/v). The arc curvature in the diagram (2b)
at NH4Cl concentration of 4 to 7% (w/v) and pH
of 5.6 is approximately similar to the curvature
of the arc at NH4Cl concentration of 4 to 7% (w
/ v) and pH value of 5.88. Based on Figure 3C,
at some vanadium concentrations (2100 mg/L),
the recovery is below 60% of vanadium. This
signicant difference is due to the insufcient
concentration of the ammonium chloride used (the
minimum concentration used was 2.98% (w/v)). It
can be concluded that the vanadium precipitation
depends on both the concentration of ammonium
chloride and the concentration of vanadium in
the leaching solution. It was also found that the
minimum concentration of ammonium chloride
used, i.e., 2.98% (w/v), is what was considered
for the formation of ammonium metavanadate.
According to Figure 3b, it is evident that the
vanadium recovery continues to grow with
increasing ammonium chloride concentration.
In this connection, the concentrated leaching
solution leads to the high recovery of up to 100%
vanadium. Fig.c also shows that the recovery of
over 80% of vanadium can be achieved with the
ammonium chloride concentration in the range
of 4 to 6% (w/v), which is economically and
industrially justied. As shown in Figure 3d, the
vanadium recovery increased from 57% to 99%
with growing ammonium chloride concentration
from 2.98% to 8.02% (w/v). It is clear that to
achieve vanadium recovery above 80%, ammonium
chloride concentrations above 4% (w/v) must
be used. From the results of the tests, it can be
concluded that the vanadium and ammonium
chloride concentrations have to be correlated with
the inverse ratio in the leaching solution so that the
vanadium concentration in the leaching solution
is less than 1000 mg L-1, which means that the
ammonium chloride requires a concentration
about 12% (w /v) to achieve vanadium recovery
of over 90%.
3.5. The effect of important parameters on
recovery of impurities
3.5.1.Aluminum recovery
Figure 4a shows the effect of pH and ammonium
chloride concentration on aluminum precipitation.
As can be seen, the amount of aluminum
precipitation grew slightly with increasing pH and
ammonium chloride concentration. In order to
reduce impurities in vanadium to a minimum, the
ammonium chloride concentration and pH value
were chosen to be in the range of 4 - 6% (w/v) and
5.5-6.5, respectively. From Figure 4b, it is known
that the higher the vanadium concentration in the
leaching solution, the more aluminum is deposited,
so that the effect of the pH value is negligible
compared to the vanadium concentration in the
leaching solution. Therefore, it is better to use
leach solutions with a higher liquid-to-solid (L/S)
ratio to minimize the amount of contamination in
vanadium. According to Figure 4c, it is clear that
the precipitation of aluminum rises with increasing
concentrations of ammonium chloride and
vanadium in the leaching solution. For example,
in a leach solution with a vanadium concentration
of 1700 mg L-1 and an ammonium chloride of
4% (w/v), the amount of aluminum precipitation
reached about 40%, while in a leach solution with
a vanadium concentration of 2500 mg L-1 and
ammonium chloride with a concentration of 7%
(w/v) is about 65%. Since our goal is to minimize
the amount of impurities in vanadium, the rst
leaching solution is preferable.
Response Surface Methodology for Recovery of Vanadium Mahshid Gharagozlou et al
72
Response Surface Methodology for Recovery of Vanadium
*Corresponding Author: Hossein Sid Kalal
E-mail address: hsidkalal@aeoi.org.ir
https://doi.org/10.24200/amecj.v4.i04.153
(a)
(b)
(c)
(d)
Fig. 3. Influence of pH value (a), Effect of ammonium chloride concentration and pH value on
vanadium recovery(b), vanadium concentration (c) and ammonium chloride concentration (d) on
the recovery of vanadium.
3.5. The effect of important parameters on recovery of impurities
3.5.1. Aluminum recovery
50
55
60
65
70
75
80
85
90
95
100
5/5 66/5 77/5
Vanadium Recovery (%)
pH
50
55
60
65
70
75
80
85
90
95
100
1400 1700 2000 2300 2600 2900
Vanadium Recovery (%)
V(ppm)
50
55
60
65
70
75
80
85
90
95
100
345678
Vanadium Recovey (%)
NH4Cl(%W/V)
95
95/5
96
96/5
97
97/5
98
98/5
99
99/5
100
57911 13 15
Vanadium recovery %
Ammonium chlorid% (w/v)
Fig. 3. Inuence of pH value (a), Effect of ammonium chloride concentration and pH value
on vanadium recovery(b), vanadium concentration (c) and ammonium chloride concentration (d)
on the recovery of vanadium
Anal. Methods Environ. Chem. J. 4 (4) (2021) 64-77
NH4Cl
(%w/v)
NH4Cl (%w/v)V (ppm)
pH
pH
73
Fig. 4. Inuence of pH value, vanadium concentration and ammonium chloride concentration on the recovery
of Aluminium (a – c) Inuence of pH value, vanadium concentration and ammonium chloride concentration
on the recovery of Molybdenum (d – f)
Response Surface Methodology for Recovery of Vanadium
*Corresponding Author: Hossein Sid Kalal
E-mail address:hsidkalal@aeoi.org.ir
https://doi.org/10.24200/amecj.v4.i04.153
(b)
(d)
(f)
Response Surface Methodology for Recovery of Vanadium Mahshid Gharagozlou et al
NH4Cl
(%w/v)
NH4Cl
(%w/v)
NH4Cl (%w/v)
NH4Cl (%w/v)
V (ppm)
V (ppm)
V (ppm)
V (ppm)
pHpH
pH
pH
74
3.5.2.Molybdenum recovery
It is clear from Figure 4d that the increase in
pH, slightly reduces the amount of molybdenum
precipitation. It is known that with increasing or
decreasing the ammonium chloride concentration,
the amount of molybdenum deposition varies
between 8% and 10%. The minimal molybdenum
precipitation is observed at an ammonium chloride
concentration of 4.5 to 5.5% (w/v) and a pH
of about 5.5 to 6.5. According to Figure 4e, it is
observed that the rising in pH leads to an increase
in the amount of molybdenum precipitation, but
this increase is more pronounced for vanadium
concentrations in leaching solution between 1700
to 2100 mg/L. Since our goal is to minimize the
amount of molybdenum precipitation, a pH in the
range of 5.5 to 6 was chosen. It is understandable
from Fig. 3f that changes in the concentrations
of ammonium chloride and vanadium in the
leaching solution have little effect on molybdenum
precipitation. According to the gure, the least
amount of molybdenum precipitation is observed at
concentrations of 5.5% (w/v) and 1200 mg L-1 for
ammonium chloride and vanadium, respectively. In
order to minimize the molybdenum precipitation, it
is better to carry out experiments in this medium.
3.5.3.Sodium recovery
Based on Figure 5a, the sodium precipitation goes
up with increasing vanadium concentration in the
leaching solution. The highest amount of sodium
precipitation was at a pH of 6.5 and a vanadium
concentration of 2500 mg L-1, and the lowest
amount was at a pH range between 5.5 to 6.5 and
a vanadium concentration of about 1700 mg L-1. In
this case, it is advisable to carry out the tests in the
minimum point range. From Figure 5b, we can nd
that that increasing the vanadium concentration in
the leaching solution leads to an expansion in the
amount of sodium precipitate. In fact, the higher the
concentration of the leach solution, the greater the
deposition of other contaminants, including sodium
along with ammonium metavanadate. Figure 5b
also shows that increasing the ammonium chloride
concentration at high vanadium concentrations
reduces sodium precipitation. On the other hand,
sodium formation is minimized at the minimum
concentration of ammonium chloride and vanadium.
Fig. 5. Inuence of pH value, vanadium concentration and ammonium chloride concentration
on the recovery of Sodium (a, b)
Response Surface Methodology for Recovery of Vanadium
*Corresponding Author: Hossein Sid Kalal
E-mail address: hsidkalal@aeoi.org.ir
https://doi.org/10.24200/amecj.v4.i04.153
6.5 and a vanadium concentration of about 1700 mg L-1. In this case, it is advisable to carry out
the tests in the minimum point range. From Figure 5b, we can find that that increasing the
vanadium concentration in the leaching solution leads to an expansion in the amount of sodium
precipitate. In fact, the higher the concentration of the leach solution, the greater the deposition of
other contaminants, including sodium along with ammonium metavanadate. Figure 5b also shows
that increasing the ammonium chloride concentration at high vanadium concentrations reduces
sodium precipitation. On the other hand, sodium formation is minimized at the minimum
concentration of ammonium chloride and vanadium.
(a)
(b)
Fig. 5. Influence of pH value, vanadium concentration and ammonium chloride concentration on
the recovery of Sodium (a, b)
3.5.4. Silicon recovery
The effect of the vanadium concentration and pH on the silicon precipitation in the leaching
solution is shown in Figure 5c. One can deduce that the higher the vanadium concentration in the
Anal. Methods Environ. Chem. J. 4 (4) (2021) 64-77
V (ppm)
V (ppm) NH4Cl (%w/v)
pH
75
3.5.4.Silicon recovery
The effect of the vanadium concentration and
pH on the silicon precipitation in the leaching
solution is shown in Figure 5c. One can deduce
that the higher the vanadium concentration in
the leaching solution, the higher the amount of
silicon precipitation. The pH parameter had no
signicant inuence on the formation of the silicon
deposit. The vanadium concentrations below 2000
mg L-1 and a pH of around 5.5 to 6.15 should be
selected to minimize silicon sedimentation. It can
be seen in Figure 5d that increasing the vanadium
concentration in the leach solution increases the
amount of silicon precipitation. An increase in the
ammonium chloride concentration also has a minor
inuence on the amount of silicon deposit. The
minimum amount of impurities can be achieved
at a concentration of 4 to 5% (w/v) ammonium
chloride and a vanadium concentration below 1000
mg L-1.
3.6. The optimal point with maximum vanadium
recovery
At the optimal point, we have the maximum
recovery of vanadium and minimum precipitation
of contaminants in the leach solution. The specied
optimal point suggested by the software has the
following conditions (Eq.1)
NH4Cl conc. = 5.48% (w/v), pH = 5.82, Vanadium
concentration in the leach solution = 1700 mg L-1
(Eq.1)
The important factors during designing the tests are
shown in Table 5. The p-value for the parameters
determines the signicance and inuence of the
factor. The more the p-value is less than 0.05,
the more effective. The parameter of Lack of t
species the tting of the data with the model.
The more the p-value for the Lack of t exceeds
0.05, the better the t. Also, the amount of (R-Sq =
98.83% or R-Sq (Adj) = 97.10%) should be taken
into account, which is acceptable for the design of
the test.
The equation 2 obtained by the software is as follows:
R.V= (+5709.94005) - (1843.48600 * pH) -(612.88936
* NH4Cl) - (1.05601* V) + (208.76649 * pH * NH4Cl)
+ (0.33175 * pH * V) + (5.05000E-003 * NH4Cl * V)+
(149.50072 * pH2 ) – (2.79322 * NH4Cl2 ) – (16.99333
* pH2 * NH4Cl) – (0.026768 * pH2 * V)
Where: NH4Cl is the concentration of ammonium
chloride, and V is the vanadium concentration in
the leach solution. According to Table 6, vanadium
with a high recovery and high purity (low
contamination) can be obtained at the point where
the software determines to be the optimal point.
Therefore, this point was considered as the optimal
point for the set of these tests.
Response Surface Methodology for Recovery of Vanadium
*Corresponding Author: Hossein Sid Kalal
E-mail address: hsidkalal@aeoi.org.ir
https://doi.org/10.24200/amecj.v4.i04.153
leaching solution, the higher the amount of silicon precipitation. The pH parameter had no
significant influence on the formation of the silicon deposit. The vanadium concentrations below
2000 mg L-1 and a pH of around 5.5 to 6.15 should be selected to minimize silicon sedimentation.
It can be seen in Figure 5d that increasing the vanadium concentration in the leach solution
increases the amount of silicon precipitation. An increase in the ammonium chloride concentration
also has a minor influence on the amount of silicon deposit. The minimum amount of impurities
can be achieved at a concentration of 4 to 5% (w/v) ammonium chloride and a vanadium
concentration below 1000 mg L-1.
(c)
(d)
Fig. 5. Influence of pH value, vanadium concentration and ammonium chloride concentration on
the recovery of Silicon (c, d)
3.6. The optimal point with maximum vanadium recovery
At the optimal point, we have the maximum recovery of vanadium and minimum precipitation of
contaminants in the leach solution. The specified optimal point suggested by the software has the
following conditions (Eq.1)
Fig. 5. Inuence of pH value, vanadium concentration and ammonium chloride concentration
on the recovery of Silicon (c, d)
Response Surface Methodology for Recovery of Vanadium Mahshid Gharagozlou et al
V (ppm) V (ppm)
pH NH4Cl (%w/v)
76
4. Conclusions
The white ammonium metavanadate was formed
with a pH value of 5 to 7. Vanadium had a high
recovery at optimized pH. The effect of time on the
vanadium recovery was examined, and it was found
that the vanadium recovery rate does not change with
increasing precipitation time. The time parameter
had only a slight inuence on the recovery rate of
impurities in the leach solution. Since our goal is
to maximize the vanadium recovery in the leach
solution and minimize the recovery of impurities,
we consider the shortest precipitation time of 2
hours. The vanadium concentration in the leach
solution plays an effective role in the formation of
precipitates. If the vanadium concentration in the
leach solution is less than 1000 mg L-1, we have to
use more concentrated ammonium chloride (12%
(w/v)) to achieve a vanadium recovery of over
90%. The higher the vanadium concentration in
the leach solution than 1000 mg L-1, the lower the
concentration of ammonium chloride (4% (w/v))
must be used to achieve a vanadium recovery
above 90%. The ammonium chloride concentration
plays the most important role in the vanadium
precipitation. A high concentration of ammonium
chloride leads to an increase in the recovery rate of
vanadium. The optimal concentration of ammonium
chloride for vanadium precipitation depends on the
vanadium concentration in the leach solution. At
high vanadium concentrations, a low concentration
of ammonium chloride can lead to a high vanadium
recovery. Concentrated ammonium chloride leads
to a high recovery of vanadium at low vanadium
concentrations.
5. Acknowledgements
The authors would like to acknowledge all those
who aided in this work, and the nuclear science and
technology research institute in Tehran for nancial
and technical supports.
6. Competing interests
The authors declare that they have no competing
interests.
Table 5. Results obtained from Design-Expert ANOVA
p-valueSource
0.3742pH
0.8193V2O5
0.0001 >NH4Cl
0.3713pH * V2O5
0.7308pH * NH4Cl
0.0006NH4Cl * V2O5
0.2031
not signicant
Lack of t
Table 6. Results obtained from the experiment at the optimal point
Vanadium
Purity %
Vanadium
recovery %
pH
ammonium chloride
% w/v
Vanadium
mg L-1
88.8997.295.825.481700
Anal. Methods Environ. Chem. J. 4 (4) (2021) 64-77
77
7. References
[1] Z. Wang, S. Zheng, S. Wang, L.I.U. Biao,
D. Wang, D.U. Hao, Y. Zhang, Research
and prospect on extraction of vanadium
from vanadium slag by liquid oxidation
technologies, Trans. Nonferrous Met. Soc.
China, 24 (2014) 1273–1288. https://doi.
org/10.1016/S1003-6326(14)63189-7
[2] R. Ahmadi, B. Sheykhi, Recovery of
vanadium from secondary tailing of iron ore
by salt roasting-alkaline leaching and solvent
extraction processes, Iran. J. Earth Sci.,
11 (2019) 30-37. https://doi.org/10.30495/
IJES.2019.664778
[3] G. Bauer, V. Güther , H. Hess, A. Otto, O.
Roidl, H. Roller, S. Sattelberger , S. Köther-
Becker, T. Beyer, Vanadium and vanadium
compounds, Wiley VCH Verlag GmbH &
Co. KGaA, Ullmann’s Encyclopedia of Ind.
Chem., (2017) 1–22. ISBN: 9783527306732,
https://doi.org/10.1002/14356007.a27_367.
pub2
[4] E. F. Baroch, U. Staff, Vanadium and
vanadium alloys, Kirk Othmer Encyclopedia
of Chemical Technology (2000) 1–18. https://
doi.org/ 10.1002/0471238961.22011401.a01.
pub2
[5] P. Cao, W.W. Meng, L. Lei, Y. Peng, Effects
of impurity on vanadium precipitatation,
Adv. Mat. Res., 634 (2013) 3128–3133.
https://doi.org/10.4028/www.scientic.net/
AMR.634-638.3128
[6] Y.M. Zhang, S.X. Bao, T. Liu, T.J. Chen
, J. Huang, The technology of extracting
vanadium from stone coal in China:
history, current status and future prospects,
Hydrometallurgy, 109 (2011) 116–124. https://
doi.org/10.1016/j.hydromet.2011.06.002
[7] H. Liu, Y.M. Zhang, J. Huang, T. Liu, N.N.
Xue, Q.H. Shi, Optimization of vanadium
(IV) extraction from stone coal leaching
solution by emulsion liquid membrane using
response surface methodology, Chem. Eng.
Res. Des., 123 (2017) 111-119. https://doi.
org/10.1016/j.cherd.2017.05.001
[8] M. Wang, X. Wang, P. Ye, Recovery of
vanadium from the precipitate obtained
by purifying the wash water formed in
rening crude TiCl4, Hydrometallurgy, 110
(2011) 40–43. https://doi.org/10.1016/j.
hydromet.2011.08.005
[9] R. Navarro, J. Guzman, I. Saucedo, J. Revilla,
E. Guibal, Vanadium recovery from oil y
ash by leaching, precipitation and solvent
extraction processes, Waste Manage., 27
(2007) 425–438. https://doi.org/10.1016/j.
wasman.2006.02.002
[10] D. He, Q. Feng, G. Zhang, L. Ou, Y. Lu,
An environmentally-friendly technology
of vanadium extraction from stone coal,
Miner. Eng., 20 (2007) 1184–1186. https://
doi.org/10.1016/j.mineng.2007.04.017
[11] E. Romanovskaia, V. Romanovski, W.
Kwapinski, I. Kurilo, Selective recovery of
vanadium pentoxide from spent catalysts
of sulfuric acid production: Sustainable
approach, Hydrometallurgy, 200
(2021)105568. https://doi.org/10.1016/j.
hydromet.2021.105568
[12] H. Peng, A literature review on leaching
and recovery of vanadium, J. Environ.
Chem. Eng., 7 (2019)103313. https://doi.
org/10.1016/j.jece.2019.103313
[13] Wang, M.; Cheng, Q.; Qi, J.Y.; Li, J.; Ning,
X.X.; Jin, J.P. Process of vanadium extraction
from stone coal vanadium ore by sulfuric
acid low temperature curing and column
leaching, Min. Metall., 29 (2020) 62–67. https://
doi.org/10.3969/j.issn.1005-7854.2020.03.013
[14] V. Zeng, C.H. Yong-Cheng, A literature
review of the recovery of molybdenum and
vanadium from spent hydro desulphurisation
catalysts, Part II: Separation and purication,
Hydrometallurgy, 98(2009) 10–20. https://
doi.org/10.1016/j.hydromet.2009.03.012
[15] Z. Zhao, M. Guo, M. Zhang, Extraction of
molybdenum and vanadium from the spent
diesel exhaust catalyst by ammonia leaching
method, J. Hazard. Mater., 286 (2015) 402–409.
https://doi.org/10.1016/j.jhazmat.2014.12.063
Response Surface Methodology for Recovery of Vanadium Mahshid Gharagozlou et al