The method of sodium tungstate solution to remove fluoride

Abstract

The invention discloses a method for removing fluorine from a sodium tungstate solution. The method comprises: adjusting the pH value of the sodium tungstate solution to 9.0-9.5, and heating to boiling, so as to obtain the sodium tungstate solution after adjusting the pH value; cooling the sodium tungstate solution after adjusting the pH value to 10‑30°C, in order to obtain a cooled sodium tungstate solution; add excess calcium carbonate to the cooled sodium tungstate solution, and react the calcium carbonate with fluorine with stirring, so as to obtain Calcium sodium tungstate mixed solution; add excessive ferrous sulfate and excessive ferrous hydroxide to the sodium tungstate mixed solution containing calcium fluoride, and make the calcium fluoride flocculate and precipitate with stirring, and standing still, so as to obtain the liquid after defluorination; and filtering the liquid after defluorination, so as to obtain the purified sodium tungstate solution. By using the method of the invention, the sodium tungstate solution can be defluorinated at low cost and high efficiency, and the fluorine removal rate can reach 93.0-96.0%.

Description

technical field

[0001] The invention relates to the field of tungsten smelting, in particular to a method for removing fluorine from a sodium tungstate solution. Background technique

[0002] Alkaline process is widely used in tungsten smelting in my country. During the alkali decomposition process of tungsten concentrate, a small amount of fluorite (CaF 2 ) reacts with NaOH to generate NaF and enters the concentrated sodium tungstate feed liquid. If it is not removed, the subsequent tungsten ion exchange process will be discharged with the exchanged liquid, polluting the environment. The fluoride ion concentration in the wastewater treated by ion exchange is as high as 100-120 mg / l, which is 10-12 times higher than the national discharge standard. At present, due to the lack of low-cost and effective fluoride removal technology, my country's tungsten smelting enterprises have not yet effectively purified the sodium fluoride produced in the production process.

[0003] Th...

Examples

Embodiment 1

[0051] The composition of the concentrated sodium tungstate solution to be treated is: fluorine (F) concentration 1230mg / L, WO 3 Concentration 206g / l, NaOH concentration 18.8g / l.

[0052] 1. Test raw materials

[0053] The composition of ammonium paratungstate crystallization mother liquor is: WO 3 Concentration 22g / l, NH 4 Cl concentration 25.5g / l

[0054] Light calcium carbonate: industrial grade; ferrous sulfate: industrial grade

[0055] 2. Experimental steps

[0056] 1) Take 1m each of the above concentrated sodium tungstate solution and ammonium paratungstate crystallization mother liquor 3 In the temperature-controlled reactor, after heating to boiling, add ammonium paratungstate crystallization mother liquor continuously and check the pH value of the solution until the final pH of the solution reaches 9.5, then cool the solution to 20°C;

[0057] 2) Divide the solutions in step 1) into 5 groups on average, and in turn, add 1.1, 1.2, 1.3, 1.4 and 1.5 times the the...

Embodiment 2

[0065] The composition of concentrated sodium tungstate solution to be tested is: F concentration 1050mg / L, WO 3 Concentration 192g / l, NaOH concentration 17.4g / l.

[0066] 1. Test raw materials

[0067] The composition of ammonium paratungstate crystallization mother liquor is: WO 3 Concentration 20.6g / l, NH 4 Cl concentration 23.2g / l

[0068] Light calcium carbonate: industrial grade; ferrous sulfate: industrial grade

[0069] 2. Experimental steps:

[0070] 1) Take 1m each of the above concentrated sodium tungstate solution and ammonium paratungstate crystallization mother liquor 3 In the temperature-controlled reactor, after heating to boiling, add ammonium paratungstate crystallization mother liquor continuously and check the pH value of the solution until the final pH of the solution reaches 9.0, then cool the solution to 30°C;

[0071] 2) Calcium carbonate was added by 1.35 times of the theoretical amount, and the reaction time was 1.5h at a stirring speed of 90rad...

technical field

[0001] The invention relates to the field of tungsten smelting, in particular to a method for removing fluorine from a sodium tungstate solution. Background technique

[0002] Alkaline process is widely used in tungsten smelting in my country. During the alkali decomposition process of tungsten concentrate, a small amount of fluorite (CaF 2 ) reacts with NaOH to generate NaF and enters the concentrated sodium tungstate feed liquid. If it is not removed, the subsequent tungsten ion exchange process will be discharged with the exchanged liquid, polluting the environment. The fluoride ion concentration in the wastewater treated by ion exchange is as high as 100-120 mg / l, which is 10-12 times higher than the national discharge standard. At present, due to the lack of low-cost and effective fluoride removal technology, my country's tungsten smelting enterprises have not yet effectively purified the sodium fluoride produced in the production process.

[0003] Th...

Examples

Embodiment 1

[0051] The composition of the concentrated sodium tungstate solution to be treated is: fluorine (F) concentration 1230mg / L, WO 3 Concentration 206g / l, NaOH concentration 18.8g / l.

[0052] 1. Test raw materials

[0053] The composition of ammonium paratungstate crystallization mother liquor is: WO 3 Concentration 22g / l, NH 4 Cl concentration 25.5g / l

[0054] Light calcium carbonate: industrial grade; ferrous sulfate: industrial grade

[0055] 2. Experimental steps

[0056] 1) Take 1m each of the above concentrated sodium tungstate solution and ammonium paratungstate crystallization mother liquor 3 In the temperature-controlled reactor, after heating to boiling, add ammonium paratungstate crystallization mother liquor continuously and check the pH value of the solution until the final pH of the solution reaches 9.5, then cool the solution to 20°C;

[0057] 2) Divide the solutions in step 1) into 5 groups on average, and in turn, add 1.1, 1.2, 1.3, 1.4 and 1.5 times the the...

Embodiment 2

[0065] The composition of concentrated sodium tungstate solution to be tested is: F concentration 1050mg / L, WO 3 Concentration 192g / l, NaOH concentration 17.4g / l.

[0066] 1. Test raw materials

[0067] The composition of ammonium paratungstate crystallization mother liquor is: WO 3 Concentration 20.6g / l, NH 4 Cl concentration 23.2g / l

[0068] Light calcium carbonate: industrial grade; ferrous sulfate: industrial grade

[0069] 2. Experimental steps:

[0070] 1) Take 1m each of the above concentrated sodium tungstate solution and ammonium paratungstate crystallization mother liquor 3 In the temperature-controlled reactor, after heating to boiling, add ammonium paratungstate crystallization mother liquor continuously and check the pH value of the solution until the final pH of the solution reaches 9.0, then cool the solution to 30°C;

[0071] 2) Calcium carbonate was added by 1.35 times of the theoretical amount, and the reaction time was 1.5h at a stirring speed of 90rad...

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