A method for separating soluble rare earth complex in magnesium sulfate wastewater

Abstract

The application discloses a method for separating soluble rare earth complex in magnesium sulfate wastewater, and belongs to the technical field of rare earth hydrometallurgy wastewater treatment. The method comprises the following steps: taking the magnesium sulfate wastewater after transformation reaction of P507 and rare earth sulfate as raw materials, adjusting the pH value, filtering, stirring the filtrate by high shear emulsification, standing, filtering, and obtaining the magnesium sulfate wastewater without rare earth complex, so that the soluble rare earth complex in the magnesium sulfate wastewater is separated. The method can effectively utilize the magnesium resources, prevent equipment and pipeline from being scaled, improve the water solubility of the magnesium sulfate wastewater, improve the filtering performance of the magnesium sulfate wastewater, and is low in water treatment cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rare earth hydrometallurgy wastewater treatment, in particular to a method for separating soluble rare earth complex in magnesium sulfate wastewater. BACKGROUND

[0002] P507 is the main rare earth extractant in the rare earth extraction process. In order to improve the organic load, magnesium hydrogencarbonate or magnesium oxide is usually saponified. After saponification, P507 will react with rare earth sulfate to produce a large amount of magnesium sulfate wastewater. Although the REO content in the magnesium sulfate wastewater is strictly reduced in production, it is impossible to completely remove it. In the presence of Cl - , the RE 3+ / RE 4+ in the magnesium sulfate wastewater will form soluble rare earth complex. After adjusting the magnesium sulfate wastewater to be alkaline, it is difficult to separate solid and liquid in the process of leaching rare earth from rare earth calcine or preparing magnesium hydrogencarbonate, which seriously affects the performance of the magnesium sulfate wastewater as process water for secondary use.

[0003] With the emphasis on environmental problems, the reuse of magnesium sulfate wastewater in the rare earth extraction process has become a technical problem for rare earth separation enterprises. The mainstream process is to concentrate and evaporate the magnesium sulfate wastewater, and to crystallize the soluble rare earth complex in the slag mainly containing magnesium sulfate heptahydrate, and to reuse the steam condensate. This process causes serious waste of magnesium resources, large equipment investment, and high water treatment cost.

[0004] Therefore, for separating the soluble rare earth complex in the magnesium sulfate wastewater, how to realize the recycling of high-magnesium wastewater is a difficult problem to be solved. SUMMARY

[0005] The purpose of the present application is to provide a method for separating the soluble rare earth complex in the magnesium sulfate wastewater to solve the problems in the background art.

[0006] The technical solution adopted by the present application is as follows:

[0007] A method for separating the soluble rare earth complex in the magnesium sulfate wastewater, comprising the following steps:

[0008] Step one, taking the magnesium sulfate wastewater after the transformation reaction of P507 organic saponified by magnesium hydrogencarbonate or magnesium oxide in the extraction line and rare earth sulfate as raw material, continuously adding calcium hydroxide slurry to adjust the pH to 7.5-14 by stirring, and filtering after neutralization to obtain calcium sulfate residue and magnesium sulfate solution;

[0009] Step two, stirring the filtrate obtained in step one in a high-shear emulsifying stirrer for 10-120 min at a stirring speed of 2000-11000 rad / min to completely emulsify the magnesium sulfate wastewater;

[0010] Step three, standing for 2h-48h, the flocculent in the solution gradually transforms from suspension to colloidal precipitate;

[0011] Step four, filtering, to obtain the magnesium sulfate wastewater solution without soluble rare earth complex.

[0012] In step one, the Mg 2+ concentration is 15-40g / L, the Cl - concentration is 0.5-10g / L, the rare earth REO content is 0.05-1.00g / L, and the H + concentration is 0.01-0.15mol / L.

[0013] As described above, due to the adoption of the technical scheme, the present application has the following beneficial effects:

[0014] The present application uses the P507 after saponification of magnesium bicarbonate or magnesium oxide and the magnesium sulfate wastewater after transformation reaction of rare earth sulfate as raw materials, adjusts the pH of the magnesium sulfate wastewater to 7.5-14 by calcium hydroxide, and stirs for a certain time by a high-shear emulsification stirrer. Under the action of high-shear emulsification, the dissolution balance of the rare earth complex in the original alkaline magnesium sulfate wastewater is destroyed, the rare earth complex is precipitated in the form of flocculent and suspended in the alkaline magnesium sulfate wastewater, the flocculent is continuously grown after standing for a period of time, and finally filtered to obtain the magnesium sulfate wastewater without rare earth complex. When used as process water, the magnesium resource can be effectively utilized, the equipment and pipeline scaling is eliminated, the water solubility of the magnesium sulfate wastewater is improved, the filtration performance of the magnesium sulfate wastewater is improved, and the water treatment cost is low. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 The process flow chart of the present application; DETAILED DESCRIPTION

[0016] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme of the embodiments of the present application will be described clearly and completely in combination with specific data in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, but not all the embodiments.

[0017] Therefore, the following detailed description of the embodiments of the present application is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0018] Embodiment 1

[0019] AsFigure 1 This embodiment provides a method for separating soluble rare earth complexes from magnesium sulfate wastewater, comprising the following steps:

[0020] Take 3000 ml of magnesium sulfate wastewater from the extraction line, which contains Mg 2+ The concentration is 15 g / L, Cl - The concentration was 1.8 g / L, the rare earth REO content was 0.1 g / L, and the C content was... [H+] =0.05mol / L, at room temperature and pressure, under normal stirring conditions, calcium hydroxide slurry was continuously added to adjust the pH to 9. After filtration, the filtrate was clear and free of impurities. The filtrate was stirred under high shear stirring conditions of 3000rad / min for 20min, and the solution turned milky white. After standing, white flocculent suspensions appeared in the solution. As time went on, they continued to grow until 24h, eventually forming a rare earth complex colloidal precipitate. After filtration, 2.3g of rare earth complex and magnesium sulfate solution without rare earth complex were obtained.

[0021] Example 2

[0022] Take 3000 ml of magnesium sulfate wastewater from the extraction line, which contains Mg 2+ The concentration is 40 g / L, Cl - The concentration was 5.7 g / L, the rare earth REO content was 0.5 g / L, and the C content was... [H+] =0.12 mol / L, at room temperature and pressure, under normal stirring conditions, calcium hydroxide slurry was continuously added to adjust the pH to 10. After filtration, the filtrate was clear and free of impurities. The filtrate was stirred under high shear stirring conditions of 9800 rad / min for 20 min, and the solution turned milky white. After standing, white flocculent suspensions appeared in the solution. As time went on, they continued to grow until 8 h, eventually forming a rare earth complex colloidal precipitate. After filtration, 8.3 g of rare earth complex and magnesium sulfate solution without rare earth complex were obtained.

[0023] Example 3

[0024] Take 3000 ml of magnesium sulfate wastewater from the extraction line, which contains Mg 2+ The concentration is 32 g / L, Cl - The concentration was 3.6 g / L, the rare earth REO content was 0.08 g / L, and the C content was... [H+] =0.08 mol / L, at room temperature and pressure, under normal stirring conditions, calcium hydroxide slurry was continuously added to adjust the pH to 7.5. After filtration, the filtrate was clear and free of impurities. The filtrate was stirred for 10 minutes under high shear stirring conditions of 9100 rad / min, and the solution turned milky white. After standing, white flocculent suspensions appeared in the solution. As time went on, they continued to grow until 24 hours later, when they finally formed a rare earth complex colloidal precipitate. After filtration, 1.7 g of rare earth complex and magnesium sulfate solution without rare earth complex were obtained.

[0025] Example 4

[0026] Take 3000 ml of magnesium sulfate wastewater from the extraction line, which contains Mg 2+ Concentration 32g / L, Cl - Concentration 9.8 g / L, rare earth REO content 1.00 g / L, C [H+] =0.08 mol / L, at room temperature and pressure, under normal stirring conditions, calcium hydroxide slurry was continuously added to adjust the pH to 14. After filtration, the filtrate was clear and free of impurities. The filtrate was stirred for 10 minutes under high shear stirring conditions of 9100 rad / min, and the solution turned milky white. After standing, white flocculent suspensions appeared in the solution. As time went on, they continued to grow until 2 hours later, when they finally formed a rare earth complex colloidal precipitate. After filtration, 13.5 g of rare earth complex and magnesium sulfate solution without rare earth complex were obtained.

[0027] Comparative Example 1

[0028] Take 3000 ml of magnesium sulfate wastewater from the extraction line, which contains Mg 2+ Concentration 32g / L, Cl - Concentration 9.8 g / L, rare earth REO content 1.00 g / L, C [H+] =0.06mol / L, at room temperature and pressure, under normal stirring conditions, calcium hydroxide slurry was continuously added to adjust the pH to 7. After filtration, the filtrate was clear and free of impurities. The filtrate was stirred under high shear stirring conditions of 8500rad / min for 10min, and the solution turned milky white. After standing, no flocculent matter appeared. After 2 hours, no precipitation occurred, and the purpose of separating soluble rare earth complexes from magnesium sulfate wastewater was not achieved.

[0029] Comparative Example 2

[0030] Take 3000 ml of magnesium sulfate wastewater from the extraction line, which contains Mg 2+ Concentration 10g / L, Cl - Concentration 7.2 g / L, rare earth REO content 0.50 g / L, C [H+] =0.01mol / L, at room temperature and pressure, under normal stirring conditions, calcium hydroxide slurry was continuously added to adjust the pH to 9.5. After filtration, the filtrate was clear and free of impurities. The filtrate was stirred under high shear stirring conditions of 9000rad / min for 20min, and the solution turned milky white. After standing, no flocculent matter appeared. After 24h, no precipitation occurred, and the purpose of separating soluble rare earth complexes from magnesium sulfate wastewater was not achieved.

[0031] Comparative Example 3

[0032] Take 3000 ml of magnesium sulfate wastewater from the extraction line, which contains Mg 2+Concentration 32g / L, Cl - Concentration 9.8 g / L, rare earth REO content 0.50 g / L, C [H+] =0.01mol / L, at room temperature and pressure, under normal stirring conditions, calcium hydroxide slurry was continuously added to adjust the pH to 9.5. After filtration, the filtrate was clear and free of impurities. The filtrate was stirred under high shear stirring conditions of 1000rad / min for 20min, and the solution did not turn milky white. After standing, no flocculent matter appeared. After 24h, no precipitation occurred, and the purpose of separating soluble rare earth complexes from magnesium sulfate wastewater was not achieved.

[0033] Comparative Example 4

[0034] Take 3000 ml of magnesium sulfate wastewater from the extraction line, which contains Mg 2+ Concentration 25g / L, Cl - Concentration 6.8 g / L, rare earth REO content <0.05 g / L, C [H+] =0.01mol / L, at room temperature and pressure, under normal stirring conditions, calcium hydroxide slurry was continuously added to adjust the pH to 9.5. After filtration, the filtrate was clear and free of impurities. The filtrate was stirred under high shear stirring conditions of 9000rad / min for 20min, and the solution turned milky white. After standing, no flocculent matter appeared. No precipitation occurred until 48h, and the purpose of separating soluble rare earth complexes from magnesium sulfate wastewater was not achieved.

Claims

1. A method for separating soluble rare earth complex from magnesium sulfate wastewater, characterized in that, The method comprises the following steps: Step one, taking the magnesium sulfate wastewater after transformation reaction of P507 organic and rare earth sulfate in the extraction line as raw material, continuously adding calcium hydroxide slurry to adjust pH to 7.5-14 by stirring, and filtering after neutralization to obtain calcium sulfate filter residue and magnesium sulfate solution; Step two, stirring the filtrate obtained in step one in a high shear emulsification stirrer for 10-120 min at a stirring speed of 2000-11000 rad / min to completely emulsify the magnesium sulfate wastewater; Step three, standing for 2-48 h to gradually convert the flocculent in the solution from suspended state to colloidal precipitate; Step four, filtering to obtain the magnesium sulfate wastewater solution without soluble rare earth complex.

2. The method for separating soluble rare earth complex from magnesium sulfate wastewater according to claim 1, characterized in that: In step one, the magnesium sulfate wastewater has a Mg 2+ concentration of 15-40 g / L, Cl - concentration of 0.5-10 g / L, rare earth REO content of 0.05-1.00 g / L, H + concentration of 0.01-0.15 mol / L.

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