Claims:CLAIMS:
We Claim,
[CLAIM 1] The present invention relates to a process of separating and separately recovering multivalent metal ions from sodium sulfate solutions
a) Providing a sodium sulfate solutions comprising multivalent metal ions, adjusting pH of sodium sulfate solution to a pH of from about 2 to about 7;
b) Contacting sodium sulfate solution with resin bed comprising a chelate ion exchange resin having iminodiacetic acid (IDA);
c) Resin bed adsorbing multivalent metal ions from sodium sulfate solution;
d) Treating chelating ion exchanger resin bed with base eluent to elute oxoanions of molybdenum, tungsten and vanadium from resin bed;
e) Rinsing chelating ion exchanger resin bed with purified feed to remove excess oxoanions and free base retained in resin bed
f) Further treating chelating ion exchanger resin bed with acid eluent to elute cobalt and nickel multivalent metal ions from resin bed; and
g) Rinsing chelating ion exchanger resin bed with purified feed to remove excess cations and free acid retained in resin bed.

[CLAIM 2] The process for separating and separately recovering multivalent metal ions from sodium sulfate solutions as claimed in claim 1 wherein pH of sodium sulfate solutions solution to a pH of from about 2 to about 7.

[CLAIM 3] The process for separating and separately recovering multivalent metal ions from sodium sulfate solutions as claimed in claim 1 wherein solution of sodium sulfate passes over the chelating ion exchanger resin bed at flow rate of 5 resin bed volumes per hour to 25 resin bed volumes per hour.

[CLAIM 4] The process for separating and separately recovering multivalent metal ions from sodium sulfate solutions as claimed in claim 1 wherein solution temperature from about 20 °C to about 50° C.

[CLAIM 5] The process for separating and separately recovering multivalent metal ions from sodium sulfate solutions as claimed in claim 1 wherein chelating ion exchanger resin bed is treating with 5 grams base per liter of purified feed to 50 grams base per liter of purified feed to elute oxoanions.

[CLAIM 6] The process for separating and separately recovering multivalent metal ions from sodium sulfate solutions as claimed in claim 1 wherein chelating ion exchanger resin bed is treating with 20 grams acid per liter of purified feed to 150 grams acid per liter of purified feed to elute cations.

[CLAIM 7] The process for separating and separately recovering multivalent metal ions from sodium sulfate solutions as claimed in claim 1 wherein sodium sulfate solution is derived as raffinate from solvent extraction process or equivalent process streams.

[CLAIM 8] The process for separating and separately recovering multivalent metal ions from sodium sulfate solutions as claimed in claim 1, wherein oxoanions of molybdenum, tungsten and vanadium.

[CLAIM 9] The process for separating and separately recovering multivalent metal ions from sodium sulfate solutions as claimed in claim 1, wherein metal cations are cobalt, nickel.

[CLAIM 10] The process for separating and separately recovering multivalent metal ions from sodium sulfate solutions as claimed in claim 1, wherein sodium sulfate solutions isgenerated as from the solvent extraction or liquid-liquid extraction systems or equivalent process streams,these multivalent metal ions imparts colour in sodium sulfate product.

[CLAIM 11] The process for separating and separately recovering multivalent metal ions from sodium sulfate solutions as claimed in claim 1, wherein the process for separating oxoanions and cations is performed in same resin bed.

[CLAIM 12] The process for separating and separately recovering multivalent metal ions from sodium sulfate solutions as claimed in claim 1, whereinoxoanionsand cations eluted in separate elution stream.

[CLAIM 13] The process for separating and separately recovering multivalent metal ions from sodium sulfate solutions as claimed in claim 1, wherein base is sodium hydroxide (NaOH).

[CLAIM 14] The process for separating and separately recovering multivalent metal ions from sodium sulfate solutions as claimed in claim 1, wherein acid is sulfuric acid (H2SO4).

[CLAIM 15] The process for separating and separately recovering multivalent metal ions from sodium sulfate solutions as claimed in claim 1, wherein process doesn’t require any additional water for elution.

, Description:FIELD OF INVENTION:
The present invention relates to a process of separating and separately recovering multivalent metal ions from sodium sulfate solutions containing ammonia. In particular, this invention relates to a process for separately recovering oxoanions and cations from sodium sulfate solutions contacting with at least one resin bed comprising a chelating ion exchange resin. More particular, oxoanions of molybdenum, tungsten, vanadium and cations such as cobalt, nickel. Sodium sulfate solutions generated from the solvent extraction or liquid-liquid extraction systems or equivalent process streams.

BACKGROUND OF THE INVENTION:

This invention relates to a process of separating valuable oxoanions and metal cations from sodium sulfate solutions by a process in which eluting oxoanions and cations separately.

While recovering metals from refinery spent catalyst by hydrometallurgy process, it involves leaching, purification and solvent extraction steps. In this process the effluent is generated which is mainly concentrated solution of sodium sulfate, with traces of multivalent metal ions. To treat this effluent in the view of zero liquid discharge one has to make sodium sulfate (Na2SO4) product out of this. Such sodium sulfate solution generally contains some amount of ammonia due to ammonia being used in solvent extraction to back extract oxoanions of molybdenum, tungsten and vanadium. At the same time sodium sulfate solution generated from cobalt and nickel solvent extraction circuit is mixed to feed to make sodium sulfate product by multi effect evaporation. Since ammonia present in the sodium sulfate solution cobalt and nickel are not precipitated at higher pH before feeding to evaporation plant. Therefore, nickel and cobalt are also contaminating sodium sulfate product. Sodium sulfate quality made from this contaminated solutions have different colour shades depending upon metal ions present in it. That will badly affect the appreciation and realisation.
The document US4966710A, discloses a method for removing magnesium and calcium from sodium sulfate solutions to render the solutions suitable for membrane processing, which comprises adjusting the pH of the solutions to about 11 to 13 with sodium hydroxide to form a precipitate containing the bulk of magnesium and calcium, removing the precipitate from the resulting partially purified sodium sulfate solution. This process fails to disclose the removal process of multivalent metal ions such as oxoanions of molybdenum, tungsten, vanadium and metal cations cobalt, nickel.

The document WO1997016376A1, discloses to recrystallize sodium sulfate recovered from scale derived from the treatment by sodium bicarbonate of fumes from glass furnaces. However, this process consumes water and leads to the discharge into the natural environment of large quantities of saline water comprising for example chlorides, sulfate and fluorides. Following process cost is high and process is energy intensive, it can lead to a lesser throughput. Recovery of oxoanions and cations separately may not be possible. Higher bleed due to higher concentration of metal ions in mother liquor after evaporation.

The document EP0001533, describes a process of purification of sodium sulfate, notably sodium sulfate containing traces of methionine. The purification is carried out in oxidising medium by a solution essentially of the group of chlorates and persulfate, then the sodium sulfate thereby treated is calcinated. This process fails to disclose the removal process of multivalent metal ions, oxoanions of molybdenum, tungsten, vanadium and metal cations cobalt, nickel.

The document US6426008B2, discloses a method for removing impurities from a brine solution. The method comprising a) adjusting the pH of the brine solution to a pH of from about 2 to about 4; b) passing the brine solution through a first functionalized resin; the first functionalized resin having functional groups capable of removing multivalent metal cations from the brine solution; c) adjusting the pH of the brine solution to a pH of from about 9 to about 11.5; and d) passing the brine solution through a second functionalized resin; the second functionalized resin having functional groups capable of removing alkaline earth metal cations from the brine solution. This process uses two resin columns which increases capital cost significantly, further it is not disclosing the removal process of multivalent metal ions oxoanions of molybdenum, tungsten, vanadium and metal cations cobalt, nickel.

Variations in colour of Na2SO4 product is occurring due to inconsistent feed with respect to multivalent metal ions. Thus it becomes necessary to separate these multivalent metal ions from sodium sulfate solutions. Without following invented process the multivalent metal ions remains in the sodium sulfate solutions, therefore there is a need for improved method of separating and separately recovering oxoanions and cations from sodium sulfate solutions. Thus, there remains in industries a need for improved process of separating and separately recovering oxoanions and cations from sodium sulfate solutions.

The process described in the present invention overcome virtually all difficulties described above and provide an effective means for the separating and separately recovering multivalent metal ions from sodium sulfate solutions.

SUMMARY OF THE INVENTION:

The main aspect of the present invention is a process for separating multivalent metal ions from sodium sulfate solutions. Further the process of separately recovering oxoanions of molybdenum, tungsten, vanadium and metal cations such as cobalt and nickel from sodium sulfate solution that is generated from the solvent extraction or liquid-liquid extraction systems or equivalent process streams.

In one aspect, of the present invention provides a process for separating and separately recovering multivalent metal ions from sodium sulfate solutions containing trace amounts of multivalent metal ions comprising:
a) Providing a sodium sulfate solutions comprising multivalent metal ions, adjusting pH of sodium sulfate solution to a pH of from about 2 to about 7;
b) Contacting sodium sulfate solution with resin bed comprising a chelate ion exchange resin having iminodiacetic acid (IDA) functional group;
c) Resin bed adsorbing multivalent metal ions from sodium sulfate solution;
d) Treating chelating ion exchanger resin bed with base and elute oxoanions of molybdenum, tungsten and vanadium from resin bed;
e) Rinsing chelating ion exchanger resin bed with purified feed to remove excess oxoanions retained in resin bed;
f) Further treating chelating ion exchanger resin bed with acid and elute cobalt and nickel metal cations from resin bed; and
g) Rinsing chelating ion exchanger resin bed with purified feed to remove excess cations retained in resin bed.

In another aspect, of the present invention provides a method for the separation of multivalent metal ions from solution of sodium sulfate containing multivalent metal ions comprising:
a) Providing a sodium sulfate solutions comprising multivalent metal ions, adjusting pH of sodium sulfate solution to a pH of from about 2 to about 7;
b) Contacting sodium sulfate solution with resin bed comprising a chelate ion exchange resin having iminodiacetic acid (IDA) functional group;
c) Resin bed adsorbing multivalent metal ions from sodium sulfate solution.

In another aspect, of the present invention provides a method for the separation and recovery of multivalent metal ions from solution of sodium sulfate containing multivalent metal ions comprising:
a) Treating chelating ion exchanger resin bed with base and elute oxoanions of molybdenum, tungsten and vanadium from resin bed;
b) Rinsing chelating ion exchanger resin bed with purified feed to remove excess oxoanions of molybdenum, tungsten and vanadium retained in resin bed;
c) Further treating chelating ion exchanger resin bed with acid and elute cobalt and nickel metal cations from resin bed; and
d) Rinsing chelating ion exchanger resin bed with purified feed to remove excess cations retained in resin bed.

In yet another aspect of the present invention is that the process for separating oxoanions and cations is single step process.

In yet another aspect of the present invention is that cations and anions eluted in separate elution stream.

In yet another aspect of the present invention is this process doesn’t require any additional water for elution; hence this process is environment friendly which conserves natural resources.

DETAILED DESCRIPTION OF FIGURES:

This invention will be better understood and the above objects as well as objects other than those set forth above will become more apparent after a study of the following detailed description thereof.
Figure 1: is a block flow diagram of separation of multivalent metal ions by adsorption on chelating ion exchange resin bed from solution of sodium sulfate containing trace amounts of multivalent metal ions adsorption.
Figure 2: is a block flow diagram of base elution and rinsing ofoxoanions from chelating ion exchange resin bed.
Figure 3: is a block flow diagram of acid elution andrinsing of cations from chelating ion exchange resin bed.

DETAILED DESCRIPTION OF THE INVENTION:

As used herein, the terms below have the meanings indicated. The singular forms "a," "an," and "the" may refer to plural articles unless specifically stated otherwise.

The term "about" as used herein, is intended to qualify the numerical valuables which it modifies, denoting such a valuable as variable within a margin of error. When no particular margin of error, such as a standard deviation to a mean valuable given in a chart or table of data, is recited, the term "about" should be understood to mean that range which would encompass the recited valuable and the range which would be included by rounding up or down to that figure as well, taking into account significant figures.

The present invention is a method for separating and separately recovering multivalent metal ions from sodium sulfate solutions from solvent extraction systems wherein valuable oxoanions of molybdenum, tungsten, vanadium and metal cations such as cobalt, nickel from sodium sulfate solutions that are generated from the solvent extraction or liquid-liquid extraction systems or equivalent process streams.

The present invention has applicability for the separation of all valuable metal ions from sodium sulfate solutions that are generated fromsolvent extraction or liquid-liquid extraction systems or equivalent process streams, for example valuable oxoanions of molybdenum, tungsten, vanadium and valuable metal cations such as cobalt, nickel fromindustrial sodium sulfate solution received from solvent extraction or liquid-liquid extraction systems or equivalent process streams process having colour imparting multivalent metal ions in it.

The chelating ion exchange resin with iminodiacetic acid functionality is a styrene-divinylbenzene (macroporous) linked to the polymer matrix. The term “styrene polymer” indicates a copolymer polymerized from a vinyl monomer or mixture of vinyl monomers containing styrene monomer and/or at least one crosslinker, wherein the combined weight of styrene and cross linkers is at least 50 weight percent of the total monomer weight. The level of cross linking ranges from 4 to 10%. All percentages herein are weight percentages.

The chelating ion exchange resin with iminodiacetic acid functionality is used to treat sodium sulfate solutions from solvent extraction systems. As used herein sodium sulfate solutions may be generated from the solvent extraction or liquid-liquid extraction systems or equivalent process streams. The raffinate sodium sulfate solution comprises multivalent metal ions. The multivalent metal ions may be oxoanions of molybdenum, tungsten, vanadium and metal cations such as cobalt, nickel.

As used herein, molybdate is present in the sodium sulfate solution in an amount from 5 ppm to 500 ppm, alternatively from 15 ppm to 150 ppm, tungstate is present in the sodium sulfate solution in an amount from 5 ppm to 500 ppm, alternatively from 15 ppm to 150 ppm, vanadate is present in the sodium sulfate solution in an amount from 5 ppm to 500 ppm, alternatively from 15 ppm to 150 ppm. Cobalt is present in the sodium sulfate solution in an amount from 5ppm to 500 ppm; alternatively from 5 ppm to 150 ppm nickel is present in the sodium sulfate solution in an amount from 5 ppm to 500 ppm, alternatively from 5 ppm to 50 ppm.

Sodium sulfate solution generated from solvent extraction systems contains about 150 to 250 grams sodium sulfate per liter of solution. The sodium sulfate solutions optionally contain a variety of other components. Such components includes: oxoanions of molybdenum, tungsten and vanadium, metal cations ofcobalt andnickel. However a typical source of these solutions is the raffinate resulting from the liquid-liquid exchange processes for extracting metals containing ammonia.

Sodium sulfate solution is primarily treated with carbon to remove trace amount of organic solvent and other impurities. In one of the embodiment of the present invention provides a method for the separation of multivalent metal ions from solution of sodium sulfatesystems containing ammonia, wherein the pH of the sodium sulfate solutions from solvent extraction systems is adjusted in the range from 2 to 7, alternatively from 4 to 5. The partially purified solution is then contacted with a chelating ion exchange resin bed having an iminodiacetic acid (IDA) functional group, to remove essentially all multivalent metal ions from sodium sulfate solution.

The preferred resin is chelating resin from M/s. Thermax under the name CH-90.

The solution ofsodium sulfate was passed over the chelating ion exchange resin bed to separate valuable multivalent metal ions from the solution. The resin bed adsorbs oxoanions of molybdenum, tungsten, vanadium and metal cations such as cobalt, nickel. Multivalent metal ions are retained in resin column, multivalent metal ions free sodium sulfate solution is used for preparing Na2SO4 product. Further the purified solution contains less than about 10 ppm metal concentrations. This purified solution can then be processed to derive pure white Na2SO4 product, instead of having variation in Na2SO4 product with respect to colour.

Once the adsorption is complete, the multivalent metal ions are recovered separately from chelating ion exchanger resin bed by base-acid elution processes.

Firstly, oxoanions of molybdenum, tungsten and vanadium eluted with base from chelating ion exchanger resin bed, followed by its rinsing with purified feed to remove oxoanions of molybdenum, tungsten and vanadium and free base. Then metal cations are recovered from chelating ion exchanger resin bed by acid elution process. The chelating ion exchanger resin bedis treated with acid for eluting metal cations such as cobalt and nickel followed by its rinse.

The elution of oxoanions can be carried out in presence of base such as sodium hydroxide (NaOH). The elution of metal cations can be carried out in presences of acid such as sulfuric acid (H2SO4).

The process of the present invention relates to separating multivalent metal ions, oxoanions of molybdenum, tungsten, vanadium and metal cations such as cobalt, nickeland separately recovering multivalent metal ions using chelating ion exchanger resin. The chelating ion exchanger resin retains multivalent metal ions. With the iminodiacetic acid functionalized resin, the selective binding of multivalent metal ions species is higher.

For recovery of metal ions, the elution phase can be a basic solution of sodium hydroxide for the recovery of oxoanions of molybdenum, tungsten and vanadium from the chelating ion exchanger resin. The elution can be sulphuric acid solution for the recovery of cations cobalt, nickel from the chelating ion exchanger resin bed. Both base-acid were added to purified feed.

Afterwards, the resin bed is rinsed with purified feed to remove multivalent metal ions and free base and acid left after each elution.

In the following examples, the feed is a sodium sulfate solutions containing ammonia. The process doesn’t require any extra water, for the preparation of base eluent and acid eluent, since these are prepared adding base and acid to purified feed and rinsing solution is again purified. Thus no other chemicals are required for further regeneration; therefore this process is advantageously more environment friendly as compared to the processes of the prior art.

WORKING EXAMPLE
REFERENCE EXAMPLE-1
Method for separation of traces of multivalent metal ions from solution of sodium sulfate (ADSORPTION)
Sodium sulfate solution received from solvent extraction process initially given carbon treatment to remove solvent traces. 145 grams sodium sulfate per liter of solution having following concentrations of multivalent metal ions about 176 ppm molybdenum, about 4.9ppm tungsten, about 137 ppm vanadium, about 32 ppm cobalt, and about 20 ppm nickel, and about 2368 ppm ammonia. A resin bed of Thermax CH-90 resin, a chelating ion exchanger with iminodiacetic acid functionality (IDA), prepared in a 100 ml column. Sodium sulfate solution containing above mentioned multivalent metal ions passed through the column at 5 resin bed volumes per hourand at a feed pH of 4.5. This passed solution following concentrations of multivalent metal ions about 4 ppm molybdenum, about <1 ppm tungsten, about 3 ppm vanadium, about <1 ppm cobalt, and about <1 ppm nickel, and about 2368 ppm ammonia.

The experiments as shown in table-1, examples 1 to 6, separation of multivalent metal ions from solution of sodium sulfate containing traces of multivalent metal ions and conditions for pursuing adsorption sodium sulfate solution is as per procedures mentioned in reference example-1.
Table-1
Example no. pH Flow rate
(BV/HR) Temperature (°C) Resin vol. (ml) Feed vol.
(liter)
1
2
3
4
5
6 4.5
4.8
4.9
6
5.6
5 5
8
8
5
10
5 30
45
20
25
22
30 100
100
100
100
100
100 8
2.1
2
2
6
4.1

Details of metal ions in feed and after treatment are shown in table-2.
Table-2
Before resin treatment (Feed) After resin treatment
Example no. Mo
(ppm) W
(ppm) V
(ppm) Co
(ppm) Ni
(ppm) NH3
(ppm) Mo
(ppm) W
(ppm) V
(ppm) Co
(ppm) Ni
(ppm) NH3
(ppm) Ads.
Capa. (mg/ml)
1
2
3
4
5
6 83
323
198
176
24
50 <1
<1
111
4.9
<1
42 <1
<1
4
137
<1
77 4.3
4.1
4
32
63
12 3.2
6.8
3.3
20
42
19 400
732
1123
2368
511
808 8.1
9
4.1
6.7
2.3
2.9 <1
<1
4.4
<1
<1
2.1 <1
<1
<1
2.7
<1
4.2 <1
<1
<1
<1
2.8
<1 <1
<1
<1
<1
3.7
<1 400
732
1123
2368
511
808 6.84
6.82
6.22
7.20
7.21
7.79

In table-2 sodium sulfate per liter of solution having following concentrations of multivalent metal ions before resin treatment. Further sodium sulfate solution treated as per procedures mentioned in reference example-1, with the mentioned conditions in table-1 the multivalent metal ions left in the treated sodium sulfate solution is as per after resin treatment data table, wherein multivalent metal ions are removed more than 90%.

REFERENCEXAMPLE-2
Method for the elution of multivalent metal ions (ELUTION)
In eluting the loaded multivalent metal ions (oxoanions and cations) from the resin, base and acids are found to be effective for separating oxoanions and cations. Therefore, NaOH and H2SO4 solutions chosen as eluent for oxoanions and cations.

In elution experiments, 20 grams NaOH per liter of purified feed is passed through column at 5 resin bed volumes per hour, which is used in eluting adsorbed oxoanions, about 813 ppm molybdenum, about 21 ppm tungsten, and about 623 ppm vanadium. This solution is further processed to recover metal ions. Followed by its rinse cycle using purified feed, passed through column at 5 resin bed volumes per hour to remove retained oxoanions and free base after elution, about19.7 ppm molybdenum, about 2 ppm tungsten, and about 12.9 ppm vanadium. Then 150 grams H2SO4 per liter of purified feed passed through column at 5 resin bed volumes per hour, which used in eluting adsorbed metal cations, about 148 ppm cobalt, about 92 ppm nickel. Followed by its rinse cycle using purified feed, passed through column at 5 resin bed volumes per hour to recover remove retained metal cations and free acid after elution,about 1.3 ppm cobalt, about 1.8 ppm nickel. This solution is further processed to recover metal ions.

The experiments as shown in table-3, examples 7 to 12, are elution of multivalent metal ions from adsorbed multivalent metal ions in examples 1 to 6 from solution of sodium sulfate, respectively. The elution of multivalent metal ions from adsorbed multivalent metal ions from sodium sulfate solution is as per procedures mentioned in reference example-2.
Table-3
Example no. % Adsorbed %
Elution
7 Mo
W
V
Co
Ni 90.24
NA
NA
95.12
92.5 96.8
NA
NA
96.64
96.68
8 Mo
W
V
Co
Ni 97.21
NA
NA
97.32
97.65 90.08
NA
NA
92.61
95.24
9 Mo
W
V
Co
Ni 97.93
95.50
95.00
96.50
92.12 98.25
95.87
94.74
96.89
96.05
10 Mo
W
V
Co
Ni 96.19
95.92
98.03
99.56
98.95 97.21
93.62
93.74
93.31
93.89
11 Mo
W
V
Co
Ni 90.42
NA
NA
95.56
91.19 96.16
NA
NA
97.51
94.34
12 Mo
W
V
Co
Ni 94.20
95.00
94.55
97.25
98.11 90.41
91.69
90.46
91.12
94.47
*NA= Not Applicable

Details of elution of multivalent metal ions from adsorbed multivalent metal ions from sodium sulfate solution wherein elution is presented in table-4.

Table-4
Oxoanions Cations
Example no. Base elution
(ppm) Rinsing (ppm) Acid elution (ppm) Rinsing (ppm)
7 Mo
W
V
Co
Ni 1450
<1
<1
<1
<1 50
<1
<1
<1
<1 <1
<1
<1
77
54 <1
<1
<1
4.1
6
8 Mo
W
V
Co
Ni 1455
<1
<1
<1
<1 60
<1
<1
<1
<1 <1
<1
<1
19
33 <1
<1
<1
<1
<1
9 Mo
W
V
Co
Ni 940
501
16
<1
<1 25
20
4
<1
<1 <1
<1
<1
18
12.4 <1
<1
<1
1.4
4.4
10 Mo
W
V
Co
Ni 813
21
623
<1
<1 19.7
2
12.9
<1
<1 <1
<1
<1
148
92 <1
<1
<1
1.3
1.8
11 Mo
W
V
Co
Ni 304
<1
<1
<1
<1
18
<1
<1
<1
<1 <1
<1
<1
876
535 <1
<1
<1
9
14
12 Mo
W
V
Co
Ni 426
363
666
<1
<1 21
24
18
<1
<1 <1
<1
<1
102
167 <1
<1
<1
14
27

Comparative Example
This example shows the necessity of removing multivalent metal ions before preparation of Na2SO4 product. We prepared two Na2SO4 products using two different feeds. One feed containing multivalent metal ions and the other one using process shown as per working examples. It shows that after following working example process we get increment in lightness index.
In two separate reactors equipped with stirring means, 145 grams sodium sulfate per liter of solutions was taken. Sodium sulfate solution before resin treatment and after resin treatment used to prepare Na2SO4 product. Sodium sulfate solution before resin treatment (about 176 ppm molybdenum, about 4.9 ppm tungsten, about 137 ppm vanadium, about 32 ppm cobalt, and about 20 ppm nickel, and about 2368 ppm ammonia ) and after resin treatment (about 6.7 ppm molybdenum, about <1 ppm tungsten, about 2.7 ppm vanadium., about <1 ppm cobalt, and about <1 ppm nickel, and about 2368 ppm ammonia ) parameters as follows: specific gravity 1.15, pH 4.5, evaporative crystallization done at 60°C and before resin treatment crystal weight is 130 g and after resin treatment crystal weight is 131 g, which is separated by solid-liquid separation known method, sodium sulfate product prepared using before resin treatment shows lightness index (L*) 91%, whereas sodium sulfate product prepared using after resin treatment sodium sulfate solution shows L* 96%.