Recovery method of tantalum-niobium hydrometallurgy acid wastewater

Abstract

The invention belongs to the technical field of wastewater treatment, and provides a recovery method of tantalum-niobium hydrometallurgy acid wastewater. The recovery method comprises the following steps: atomizing the tantalum-niobium wet smelting acidic wastewater, performing flash evaporation, and respectively collecting to obtain volatile acid and residual liquid; and filtering the residual liquid to obtain the non-volatile acid. According to the recovery method, after the tantalum-niobium hydrometallurgy acid wastewater is atomized, flash evaporation is carried out, the flash evaporation can realize separation of volatile acids (hydrofluoric acid, fluosilicic acid and fluotitanic acid) and non-volatile acids (sulfuric acid), and the mass fraction of the sulfuric acid in the non-volatile acids is 70-80%, and the sulfuric acid can be used for ore decomposition; the volatile acid can be used for preparing potassium fluosilicate and potassium fluotitanate; and the sludge yield is low, and the hazardous waste disposal cost is reduced. The flash evaporation operation is simple, the equipment is easy to operate, the requirement for the overall quality of operators is low, and the method is easier to popularize.

Description

Technical Field

[0002] The present invention relates to the technical field of wastewater treatment, and particularly relates to a method for recycling acidic wastewater from wet smelting of tantalum and niobium. Background Art

[0003] In the process of tantalum and niobium smelting, generally, tantalum and niobium ores are first decomposed by acid, and most of the tantalum and niobium enter the decomposition liquid. Then, HF-H2SO4-MIBK / sec-octanol is used to extract and separate the decomposition liquid to obtain tantalum and niobium. During the acid decomposition process, residual ore and filter residue are also obtained; since a large amount of acid is contained in the residual ore and filter residue, before further leaching, the residual ore and filter residue need to be washed with water, and a large amount of acidic wastewater will be generated during the washing process; the acid concentration in this acidic wastewater (hereinafter referred to as acidic wastewater from wet smelting of tantalum and niobium) is low and cannot be directly reused, and generally, it is diluted and directly discharged, resulting in waste of resources.

[0004] Currently, the domestic treatment methods for acidic wastewater generated in other sections during the tantalum and niobium smelting process include electrodialysis method and lime precipitation method. In the electrodialysis method, sulfuric acid, fluosilicic acid, fluotitanic acid, etc. in the acidic wastewater are first separated and recycled to production, and the remaining residual liquid wastewater enters the neutralization precipitation system. The electrodialysis method does not require the addition of chemicals, has low energy consumption, and can be continuously operated, which is suitable for industrial production; however, the electrodialysis equipment is complex, the operation difficulty is high, and the overall quality requirements for operators are high, which limits its application. In addition, sulfuric acid cannot be recovered by electrodialysis. In the lime precipitation method, quicklime is a commonly used chemical, which has a low price and is easy to obtain, but there is a defect of a large amount of sludge production when directly using limestone for precipitation. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a method for recycling acidic wastewater from wet smelting of tantalum and niobium. The recycling method provided by the present invention can separate the volatile acid and non-volatile acid in the acidic wastewater from wet smelting of tantalum and niobium, realize the recycling and reuse of the volatile acid and non-volatile acid, and at the same time, the sludge production is small.

[0006] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a method for recycling acidic wastewater from wet smelting of tantalum and niobium, comprising the following steps:

[0008] After atomizing the acidic wastewater from wet smelting of tantalum and niobium, perform flash evaporation, and respectively collect the volatile acid and the residual liquid;

[0009] Filter the residual liquid to obtain the non-volatile acid.

[0010] Preferably, the acidic wastewater from wet smelting of tantalum and niobium comprises: Si 1 - 30 g / L, Ti 0.5 - 20 g / L, F 20 - 150 g / L, HF 1 - 2 mol / L, H2SO4 3 - 5 mol / L.

[0011] Preferably, the atomizing device is a high-pressure nozzle.

[0012] Preferably, the apparent positive pressure of the atomization is 0.03 - 0.06 MPa.

[0013] Preferably, the apparent negative pressure of the flash evaporation is -0.6 - -0.8 MPa.

[0014] Preferably, the temperature of the flash evaporation is 200 - 300 °C.

[0015] Preferably, the volatile acid is used for preparing potassium fluorosilicate and potassium fluotitanate.

[0016] Preferably, the filtering device is a horizontal plate and frame filter.

[0017] Preferably, the non-volatile acid is recycled for ore decomposition.

[0018] Preferably, in the filtering, a filter cake is further obtained, and the filter cake is used for further metal recovery.

[0019] The present invention provides a method for recycling acidic wastewater from wet smelting of tantalum and niobium.

[0020] In the recycling method of the present invention, after atomizing the acidic wastewater from wet smelting of tantalum and niobium, flash evaporation is carried out. Flash evaporation can realize the separation of volatile acids (hydrofluoric acid, fluorosilicic acid and fluotitanic acid) and non-volatile acid (sulfuric acid). Among them, the non-volatile acid can be recycled for ore decomposition, and the volatile acid can be used for preparing potassium fluorosilicate and potassium fluotitanate, realizing the resource utilization of the acidic wastewater from wet smelting of tantalum and niobium. The present invention separately collects the volatile acid and the non-volatile acid, so that the output of the filter cake (sludge) generated in the system is low, the hazardous waste treatment cost is low, and the filter cake can further be used for metal recovery, which can further reduce the sludge output. The flash evaporation operation of the present invention is simple, the equipment is easy to operate, the overall quality requirement for the operators is low, and it is easier to promote. Detailed Embodiments

[0021] The present invention provides a method for recycling acidic wastewater from wet smelting of tantalum and niobium, comprising the following steps:

[0022] After atomizing the acidic wastewater from wet smelting of tantalum and niobium, flash evaporation is carried out, and the volatile acid and the residual liquid are separately collected;

[0023] The residual liquid is filtered to obtain the non-volatile acid.

[0024] Unless otherwise specified, the raw materials used in the present invention are preferably commercially available products.

[0025] In the present invention, the acidic wastewater from wet smelting of tantalum and niobium is atomized and then flash evaporated, and volatile acids and residual liquid are respectively collected.

[0026] In the present invention, the acidic wastewater from wet smelting of tantalum and niobium preferably includes H2SO4, HF, H2SiF6, H2TiF6, and NH4 + , Fe 3+ , Zn 2+ , Cr 2+ and Ni 2+ . In the present invention, the acidic wastewater from wet smelting of tantalum and niobium preferably includes: Si 1 - 30 g / L, Ti 0.5 - 20 g / L, F 20 - 150 g / L, HF 1 - 2 mol / L, H2SO4 3 - 5 mol / L. In the present invention, the Si in the acidic wastewater from wet smelting of tantalum and niobium is derived from fluosilicic acid (H2SiF6). In the present invention, the Ti in the acidic wastewater from wet smelting of tantalum and niobium is derived from fluotitanic acid (H2TiF6). In the present invention, the F in the acidic wastewater from wet smelting of tantalum and niobium is the total fluorine content, including free fluorine and fluorate.

[0027] In the present invention, the atomizing device is preferably a high-pressure nozzle. In the present invention, the apparent positive pressure of the atomization is preferably 0.03 - 0.06 MPa, specifically preferably 0.03 MPa, 0.04 MPa, 0.05 MPa, or 0.06 MPa. In the present invention, the atomization can make the acidic wastewater from wet smelting of tantalum and niobium into small particle droplets, making the flash evaporation more complete.

[0028] In the present invention, the apparent negative pressure of the flash evaporation is preferably -0.6 - -0.8 MPa, specifically it can be -0.6 MPa, -0.65 MPa, -0.7 MPa, -0.75 MPa, or -0.8 MPa. In the present invention, the temperature of the flash evaporation is preferably 200 - 300 °C, further preferably 220 - 280 °C, specifically it can be 200 °C, 210 °C, 220 °C, 230 °C, 240 °C, 250 °C, 260 °C, 270 °C, 280 °C, 290 °C, or 300 °C. By controlling the temperature and pressure of the flash evaporation in the present invention, a relatively large amount of non-volatile acid can be separated, and the content of impurities (hydrofluoric acid) in the non-volatile acid is low, the impurity ions that can be combined are few, and the impurities in the non-volatile acid are few, which is more conducive to the reuse of the non-volatile acid.

[0029] In the present invention, the volatile acids preferably include hydrofluoric acid, fluosilicic acid, and fluotitanic acid. In the present invention, the volatile acids are preferably used to prepare potassium fluorosilicate and potassium fluotitanate.

[0030] In the present invention, the flash evaporation can separate volatile acids from non-volatile acids, and the operation is simple, and the equipment used is easy to operate.

[0031] After obtaining the residual liquid, the present invention filters the residual liquid to obtain non-volatile acids.

[0032] In the present invention, the equipment for filtration is preferably a horizontal plate and frame filter.

[0033] In the present invention, the non-volatile acids preferably include sulfuric acid, and the mass fraction of sulfuric acid is 70-80%. In the present invention, the non-volatile acids are preferably recycled for ore decomposition. In the non-volatile acids obtained in the present invention, the sulfuric acid content is high and the impurity content is low, enabling it to be recycled for ore decomposition more safely and effectively.

[0034] In the present invention, for the filtration, preferably a filter cake is also obtained, and the filter cake is preferably used for further metal recovery. The present invention does not specifically limit the method for recovering the metal, and those skilled in the art can set it according to actual needs.

[0035] In the present invention, the filter cake preferably contains iron salts, zinc salts, chromium salts and nickel salts; during the flash evaporation process, metal ions will combine with sulfate radicals in the residual liquid to form sulfates. As the flash evaporation proceeds, the content of metal sulfates becomes more and more, and when it exceeds the solubility, part of it will precipitate. The present invention separately collects volatile acids and non-volatile acids. Since the acids in the acidic wastewater from the wet smelting of tantalum and niobium are not converted into sludge, only a small amount of metal salts in the acidic wastewater from the wet smelting of tantalum and niobium precipitate to produce a filter cake (i.e., sludge), greatly reducing the sludge production. At the same time, if the filter residue is further processed to recover metals, the sludge production can be further reduced.

[0036] The following is a detailed description of the method for recovering acidic wastewater from the wet smelting of tantalum and niobium provided by the present invention in combination with examples, but they should not be construed as limiting the protection scope of the present invention.

[0037] Example 1

[0038] (1) Take 20 m of acidic wastewater from the wet smelting of tantalum and niobium 3 , wherein, Si is 1.86 g / L, Ti is 10.23 g / L, F is 40.95 g / L, HF is 2 mol / L, and H2SO4 is 5 mol / L.

[0039] (2) After the acidic wastewater from the wet smelting of tantalum and niobium is atomized by a high-pressure nozzle (the apparent positive pressure of the atomization pressure is 0.03 MPa), it is flash-evaporated at an apparent negative pressure of -0.6 MPa and 260 °C, and a total of 12.7 m of volatile acids are obtained 3 , and then the residual liquid is filtered through a horizontal plate and frame filter to obtain 6.4 m of non-volatile acids 3 and 0.36 tons of filter cake.

[0040] It is determined that in the volatile acid, Si is 2.86 g / L, Ti is 14.68 g / L, and F is 62.63 g / L; in the non-volatile acid, HF is 0.05 mol / L and the mass fraction of sulfuric acid is 72.01%.

[0041] Example 2

[0042] (1) Take 20 m of acidic wastewater from the wet smelting of tantalum and niobium. 3 , where: Si is 2.64 g / L, Ti is 8.52 g / L, F is 81.7 g / L, HF is 2 mol / L, and H2SO4 is 5 mol / L.

[0043] (2) After the acidic wastewater from the wet smelting of tantalum and niobium is atomized by a high-pressure nozzle (the apparent positive pressure of the atomization pressure is 0.03 MPa), it is flash-evaporated at an apparent negative pressure of -0.6 MPa and 220 °C, and a total of 14.7 m of volatile acid is obtained. 3 , and then the residual liquid is filtered by a horizontal plate and frame filter to obtain 5.3 m of non-volatile acid. 3 and 0.5 tons of filter cake.

[0044] It is determined that in the volatile acid, Si is 3.43 g / L, Ti is 10.62 g / L, and F is 73.6 g / L; in the non-volatile acid, HF is 0.6 mol / L and the mass fraction of sulfuric acid is 71.06%.

[0045] Example 3

[0046] (1) Take 20 m of acidic wastewater from the wet smelting of tantalum and niobium. 3 , where Si is 18.21 g / L, Ti is 16.17 g / L, F is 129.6 g / L, HF is 1 mol / L, and H2SO4 is 4 mol / L.

[0047] (2) After the acidic wastewater from the wet smelting of tantalum and niobium is atomized by a high-pressure nozzle (the apparent positive pressure of the atomization pressure is 0.03 MPa), it is flash-evaporated at an apparent negative pressure of -0.6 MPa and 200 °C, and a total of 13 m of volatile acid is obtained. 3 , and then the residual liquid is filtered by a horizontal plate and frame filter to obtain 5.6 m of non-volatile acid. 3 and 3.4 tons of filter cake.

[0048] It is determined that in the volatile acid, Si is 6.49 g / L, Ti is 22.65 g / L, and F is 160 g / L; in the non-volatile acid, HF is 0.1 mol / L and the mass fraction of sulfuric acid is 70.57%.

[0049] Example 4

[0050] The difference from Example 1 is that the temperature of flash evaporation is 300 °C, and the others are the same as in Example 1.

[0051] 15.1 m of volatile acid was obtained 3 , 4.9 m of non-volatile acid 3 and 0.58 tons of filter cake.

[0052] It was determined that in the volatile acid, Si was 2.26 g / L, Ti was 10.24 g / L, and F was 37.42 g / L; in the non-volatile acid, HF was 0.03 mol / L and the mass fraction of sulfuric acid was 78.42%.

[0053] Comparative Example 1

[0054] The difference from Example 1 is that the temperature of flash evaporation is 180 °C, and the others are the same as in Example 1.

[0055] 11.8 m of volatile acid was obtained 3 , 8.2 m of non-volatile acid 3 and 0.24 tons of filter cake.

[0056] It was determined that in the volatile acid, Si was 2.38 g / L, Ti was 10.54 g / L, and F was 64.2 g / L; in the non-volatile acid, HF was 0.2 mol / L and the mass fraction of sulfuric acid was 60.79%.

[0057] Comparative Example 2

[0058] The difference from Example 1 is that the apparent negative pressure of flash evaporation is -0.9 MPa, and the others are the same as in Example 1.

[0059] 15.8 m of volatile acid was obtained 3 , 4.2 m of non-volatile acid 3 and 0.72 tons of filter cake.

[0060] It was determined that in the volatile acid, Si was 2.18 g / L, Ti was 9.74 g / L, and F was 60.45 g / L; in the non-volatile acid, HF was 0.08 mol / L and the mass fraction of sulfuric acid was 80.51%.

[0061] Comparative Example 3

[0062] The difference from Example 1 is that the apparent negative pressure of flash evaporation is -0.5 MPa, and the others are the same as in Example 1.

[0063] 12.1 m of volatile acid was obtained 3 , 7.9 m of non-volatile acid 3 and 0.2 tons of filter cake.

[0064] It is determined that in the volatile acid, Si is 2.45 g / L, Ti is 11.62 g / L, and F is 32.54 g / L; in the non-volatile acid, HF is 0.6 mol / L and the mass fraction of sulfuric acid is 68.25%.

[0065] Comparative Example 4

[0066] For the 20 m in Example 1 3 Limestone precipitation is carried out on the acidic wastewater from the wet smelting of tantalum and niobium, and as a result, 3.17 tons of sludge is produced.

[0067] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for recovering acidic wastewater from wet smelting of tantalum and niobium, characterized in that, It includes the following steps: After atomizing the acidic wastewater from the wet smelting of tantalum and niobium, perform flash evaporation to separately collect the volatile acid and the residual liquid; Filter the residual liquid to obtain the non-volatile acid.

2. The recovery method according to claim 1, wherein The acidic wastewater from the wet smelting of tantalum and niobium includes: Si 1 - 30 g / L, Ti 0.5 - 20 g / L, F 20 - 150 g / L, HF 1 - 2 mol / L, H2SO4 3 - 5 mol / L.

3. The recovery method according to claim 1, wherein The atomizing device is a high-pressure nozzle.

4. The recovery method according to claim 1 or 3, characterized in that, The apparent positive pressure of the atomizing is 0.03 - 0.06 MPa.

5. The recycling method according to claim 1, characterized in that, The apparent negative pressure of the flash evaporation is -0.6 - -0.8 MPa.

6. The recovery method according to claim 1 or 5, characterized in that, The temperature of the flash evaporation is 200 - 300 °C.

7. The recycling method according to claim 1, wherein The volatile acid is used to prepare potassium fluorosilicate and potassium fluotitanate.

8. The recycling method according to claim 1, wherein The filtering device is a horizontal plate and frame filter.

9. The recycling method according to claim 1, characterized in that, The non-volatile acid contains sulfuric acid, and the mass fraction of the sulfuric acid is 70 - 80%; the non-volatile acid is recycled for ore decomposition.

10. The recycling method according to claim 1, characterized in that, For the filtering, a filter cake is also obtained, and the filter cake is used for further metal recovery.