A rare earth liquid value adjustment process

Abstract

The invention discloses a rare earth feed liquid adjustment process, belongs to the field of hydrometallurgy, and specifically relates to the field of rare earth adjustment, so as to solve the problem that salt is introduced into the adjustment process and the concentration of the feed liquid is reduced. In addition, the alkali conversion wastewater is not promoted and recycled because the alkali concentration of the regenerated liquid is lower than that of the alkali conversion wastewater. The process includes the following steps: taking 1L of feed liquid for adjustment test, and obtaining the required alkaline substance content of the total rare earth feed liquid to be adjusted by amplification calculation; removing fluorine and phosphorus in the alkali conversion wastewater to obtain a low-concentration alkali solution; mixing the rare earth feed liquid a to be adjusted with the low-concentration alkali solution to obtain a mixed slurry, and preparing an alkali cake; taking the rare earth feed liquid b to be adjusted and mixing it with the alkali cake to obtain an adjustment slurry; mixing the adjustment slurry with the remaining rare earth feed liquid c to be adjusted, and separating the solid and liquid to obtain a rare earth neutralization liquid. The recycling of alkali conversion wastewater is realized, the pressure of wastewater treatment and discharge is reduced, the concentration of the feed liquid in the rare earth feed liquid adjustment process is reduced to a small extent or slightly increased, and the amount of salt brought into the rare earth feed liquid during the adjustment process is extremely small.

Description

Technical Field

[0001] The invention discloses a rare earth liquid value adjustment process, belonging to the field of hydrometallurgy, and specifically relates to the technical field of rare earth value adjustment. Background Art

[0002] Rare earth elements are known as "vitamins of industry" and have irreplaceable excellent magnetic, optical and electrical properties. They play a huge role in improving product performance, increasing product variety and improving production efficiency. Due to their great effects and small usage, rare earths have become an important element for improving product structure, increasing scientific and technological content and promoting technological progress in the industry. They are widely used in new materials fields such as aerospace, military, electronics, metallurgy, petrochemicals, glass ceramics, medicine, and agriculture.

[0003] At present, there are two main ways to adjust the rare earth industry. One is to directly use high-concentration liquid alkali or ammonia water for adjustment. When the concentration of the liquid is high, it will produce insoluble rare earth hydroxide lumps, resulting in a long adjustment time. The other is to use recycled rare earth carbonate or mineral adjustment. Although it solves the problem of reduced liquid concentration, the adjustment speed is also slow.

[0004] The processing of Sichuan fluorocarbon cerium ore and American ore mainly involves alkali conversion to treat rare earth fluoride and rare earth phosphate. Therefore, alkali-to-water washing uses a large amount of water and produces a large amount of low-alkalinity wastewater containing fluorine and phosphorus. The wastewater is currently not utilized as a resource.

[0005] Alkali conversion wastewater is usually treated by neutralizing it with hydrochloric acid and then adding calcium chloride to remove fluorine. The low-concentration liquid alkali is not recovered. The process of using lime to remove fluorine and phosphorus in wastewater is an existing process, but due to the limitation of fluorine and phosphorus concentrations in the wash water, the concentration of the regenerated liquid alkali is less than 50g / l, and the evaporation concentration consumes a lot of energy and has high costs. Due to its low concentration and limited alkali conversion amount, it has not been promoted in the rare earth industry. Summary of the invention

[0006] The purpose of the present invention is to provide a rare earth feed liquid adjustment process to solve the problems of salt introduction and reduced feed liquid concentration in the existing adjustment process, and the alkali conversion wastewater is not widely recovered because the alkali concentration of the regenerated liquid is lower than that of the raw earth feed liquid.

[0007] The technical solution adopted by the present invention is as follows:

[0008] A rare earth liquid value adjustment process comprises the following steps:

[0009] Step 1, obtaining the required alkaline substance content of the total rare earth solution to be adjusted;

[0010] Step 2, the alkaline substance is alkali-converted wastewater, and the alkali-converted wastewater with a sodium hydroxide content of 5-20 g / l is taken. The content of sodium hydroxide in the alkali-converted wastewater is the content of the alkaline substance required for the total rare earth feed solution to be adjusted obtained in step 1. The fluorine and phosphorus in the alkali-converted wastewater are removed by causticizing regeneration to obtain a low-concentration alkali solution;

[0011] Step 3, taking the rare earth liquid a to be adjusted, mixing the rare earth liquid a to be adjusted with a low-concentration alkali solution to obtain a mixed slurry, ensuring that the rare earth in the mixed slurry is completely precipitated, and the pH of the mixed slurry is 7-8 when the rare earth is completely precipitated, and preparing an alkali cake;

[0012] Step 4, taking the rare earth material liquid b to be adjusted and mixing it with the alkali cake, the liquid-to-solid ratio is 1:1-6:1, and the adjusted slurry is obtained;

[0013] Step 5: Mix the adjusted slurry with the remaining rare earth liquid c to be adjusted, stir to react, and separate the solid and liquid to obtain a rare earth neutralized liquid.

[0014] In the technical scheme of the present application, the sum of the rare earth solution a to be adjusted, the rare earth solution b to be adjusted and the rare earth solution c to be adjusted is the amount of the total rare earth solution to be adjusted, and the required alkaline substance content of the total rare earth solution to be adjusted is obtained. The fluorine-containing wastewater after the alkali conversion slurry is washed with water, that is, the alkali conversion wastewater, the content of sodium hydroxide in the alkali conversion wastewater is the required alkaline substance content of the total rare earth solution to be adjusted, and then the fluorine and phosphorus in the alkali conversion wastewater are removed to obtain a low-concentration alkali solution, the rare earth solution a to be adjusted is taken and mixed with the low-concentration alkali solution to obtain a mixed slurry, the amount of rare earth solution a to be adjusted is added to completely precipitate the rare earth in the mixed slurry, and the pH of the mixed slurry when the precipitation is complete is 2. 7-8, prepare alkali cake, take rare earth liquid b to be adjusted and mix it with alkali cake, liquid-solid ratio is 1:1-6:1, obtain adjustment slurry, mix the adjustment slurry with the remaining rare earth liquid c to be adjusted, stir to react, separate solid and liquid to obtain rare earth neutralization liquid. The fluorine-containing wastewater after washing the alkali conversion slurry, that is, the sodium hydroxide in the alkali conversion wastewater is fully utilized as an alkaline substance, the alkali conversion wastewater is recycled, the wastewater treatment and discharge pressure is reduced, the concentration of the rare earth liquid is reduced slightly or slightly increased during the adjustment process, and the amount of salt brought into the rare earth liquid during the adjustment process is very small.

[0015] Preferably, in step 1, 1 L of rare earth solution to be adjusted is taken and adjusted to pH 4.5 to obtain the content of consumed alkaline substances, and the total amount of alkaline substances required for the total rare earth solution to be adjusted is obtained by amplification calculation.

[0016] Preferably, in step 2, the contents of fluorine and phosphorus in the alkali-conversion wastewater are detected, and calcium oxide in an amount of 1.1-1.3 times the mass of fluorine and phosphorus is added to remove the fluorine and phosphorus in the alkali-conversion wastewater.

[0017] More preferably, 1.2 times the mass of fluorine and phosphorus is added to calcium oxide to remove fluorine and phosphorus from the alkali wastewater.

[0018] Preferably, after complete precipitation in step 3, AM flocculation is used, and alkali cake is prepared after plate and frame filtration.

[0019] Preferably, the alkaline substance in step 2 is sodium hydroxide, and the content of sodium hydroxide is the content of the alkaline substance required for the total rare earth solution to be adjusted obtained in step 1. In step 3, the rare earth solution a to be adjusted is taken, and the rare earth solution a to be adjusted is mixed with a sodium hydroxide solution to obtain a mixed slurry, and the rare earth in the mixed slurry is ensured to be completely precipitated. When the rare earth is completely precipitated, the pH of the mixed slurry is 7-8, and an alkali cake is prepared. After complete precipitation, it needs to be diluted, flocculated, washed and desalted before plate and frame filter pressing to prepare an alkali cake.

[0020] Preferably, the sum of the rare earth solution a to be adjusted, the rare earth solution b to be adjusted and the rare earth solution c to be adjusted is the total amount of the rare earth solution to be adjusted.

[0021] Preferably, in step 4, the liquid-to-solid ratio is 2:1.

[0022] Preferably, in step 5, the pH of the adjusted slurry after mixing with the remaining rare earth solution c to be adjusted is 4-4.5, and the adjustment is performed by stirring and reacting at 30-60° C. for 10-40 minutes.

[0023] More preferably, in step 5, the pH of the adjusted slurry after mixing with the remaining rare earth solution c to be adjusted is 4.2, and the mixture is stirred and reacted at 45° C. for 25 minutes.

[0024] Preferably, in step 5, adjusted slag (REO<0.5%) is also obtained, and the pH of the rare earth neutralization solution is 4-4.5.

[0025] In this application, PAM is the abbreviation of polyacrylamide (flocculant).

[0026] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0027] 1. In the present invention, the concentration of the rare earth liquid is reduced slightly or slightly increased during the rare earth liquid adjustment process, and the amount of salt introduced into the rare earth liquid during the adjustment process is very small;

[0028] 2. In the present invention, the fluorine-containing wastewater after the alkali conversion slurry is washed with water, that is, the sodium hydroxide in the alkali conversion wastewater is fully utilized as an alkaline substance, so that the alkali conversion wastewater is recycled and utilized, and the pressure of wastewater treatment and discharge is reduced;

[0029] 3. In the present invention, the entire process is economical, environmentally friendly and has low operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The present invention is a flow chart of a rare earth liquid value adjustment process. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] Example 1

[0033] like Figure 1 As shown, a rare earth liquid value adjustment process comprises the following steps:

[0034] Step 1, obtaining the content of alkaline substances required for the total rare earth solution to be adjusted, taking 1L of the rare earth solution to be adjusted to pH 4.5, obtaining the content of the consumed alkaline substances, and obtaining the total amount of alkaline substances required for the total rare earth solution to be adjusted by amplification calculation;

[0035] Step 2, the alkaline substance is alkali-conversion wastewater, and the alkali-conversion wastewater with a sodium hydroxide content of 8 g / l is taken. The content of sodium hydroxide in the alkali-conversion wastewater is the content of the alkaline substance required for the total rare earth feed solution to be adjusted in step 1, and the fluorine and phosphorus in the alkali-conversion wastewater are removed by causticizing regeneration to obtain a low-concentration alkali solution, and the content of fluorine and phosphorus in the alkali-conversion wastewater is detected, and calcium oxide with a mass of fluorine and phosphorus 1.3 times is added to remove the fluorine and phosphorus in the alkali-conversion wastewater;

[0036] Step 3, taking the rare earth liquid a to be adjusted, mixing the rare earth liquid a to be adjusted with a low-concentration alkali solution to obtain a mixed slurry, ensuring that the rare earth in the mixed slurry is completely precipitated, the pH of the mixed slurry is 7 when the precipitation is complete, preparing an alkali cake, using AM for flocculation after complete precipitation, and preparing an alkali cake after plate and frame filtration;

[0037] Step 4, taking the rare earth material liquid b to be adjusted and mixing it with the alkali cake, with a liquid-to-solid ratio of 1:1, to obtain an adjusted slurry;

[0038] Step 5, mixing the adjusted slurry with the remaining rare earth liquid c to be adjusted, stirring to react, and separating the solid and liquid to obtain a rare earth neutralized liquid and an adjusted slag (REO<0.5%). The pH of the adjusted slurry after mixing with the remaining rare earth liquid c to be adjusted is 4.5. Stirring and reacting at 60°C for 10 minutes, the pH of the rare earth neutralized liquid is 4.5; the sum of the rare earth liquid a to be adjusted, the rare earth liquid b to be adjusted, and the rare earth liquid c to be adjusted is the total amount of the rare earth liquid to be adjusted.

[0039] Example 2

[0040] like Figure 1As shown, on the basis of Example 1, the alkaline substance in step 2 is sodium hydroxide, and the content of sodium hydroxide is the content of the alkaline substance required for the total rare earth feed liquid to be adjusted in step 1. In step 3, the rare earth feed liquid a to be adjusted is taken, and the rare earth feed liquid a to be adjusted is mixed with the sodium hydroxide solution to obtain a mixed slurry, and the rare earth in the mixed slurry is ensured to be completely precipitated. When the mixed slurry is completely precipitated, the pH of the mixed slurry is 7, and an alkali cake is prepared. After complete precipitation, it needs to be diluted, flocculated, washed and desalted before plate and frame filter pressing to prepare an alkali cake. The remaining steps are the same as in Example 1.

[0041] Example 3

[0042] like Figure 1 As shown, based on Example 1, a rare earth liquid value adjustment process includes the following steps:

[0043] Step 2, the alkaline substance is alkali-converted wastewater, and the alkali-converted wastewater with a sodium hydroxide content of 12 g / l is taken; calcium oxide with a mass of 1.2 times that of fluorine and phosphorus is added to remove fluorine and phosphorus in the alkali-converted wastewater;

[0044] Step 3, pH of the mixed slurry at the time of complete precipitation is 8;

[0045] Step 4, liquid-to-solid ratio 2:1;

[0046] Step 5: The pH of the adjusted slurry after mixing with the remaining rare earth solution c to be adjusted is 4, and the mixture is stirred at 30° C. for 40 minutes, and the pH of the rare earth neutralization solution is 4. The remaining steps are the same as those described in Example 1.

[0047] Test Example 1

[0048] like Figure 1 As shown, alkali wastewater: NaOH 7.05g / l, F 5.65g / l, P 5PPM; rare earth liquid H + 20g / l, REO213g / l, Fe2O3 12g / l, Al2O3 1.03g / l; effective calcium oxide content in lime is 85%;

[0049] Take 3L of alkali wastewater, add 39g of lime and stir for 30 minutes, then separate the solid and liquid and test the supernatant NaOH 18g / lF 0.08g / l, P 1PPM;

[0050] Take 1L of rare earth material solution to be adjusted and use 50% liquid caustic soda to adjust the value, consuming 81.6g of 50% liquid caustic soda;

[0051] Take 240ml of unadjusted rare earth liquid and place it in a 3000ml beaker, add 2.3L of regenerated alkali after F removal to completely precipitate the rare earth, add flocculant to precipitate and filter to obtain alkali cake;

[0052] Take 300 ml of unadjusted rare earth liquid and add alkali cake to adjust the slurry to obtain adjusted slurry;

[0053] The adjusted slurry was transferred to the remaining rare earth liquid to be adjusted, stirred at 35°C for 35 minutes, and the endpoint pH was 4.5;

[0054] Solid-liquid separation:

[0055] Neutralizing solution: REO 206g / l, Fe2O3 0.01g / l, Al2O3 0.01g / l;

[0056] Adjusted slag: REO 0.48%.

[0057] Test Example 2

[0058] like Figure 1 As shown, alkali wastewater: NaOH 7.05g / l, F 5.65g / l, P 5PPM; rare earth feed liquid: H + 20g / l, REO213g / l, Fe2O3 12g / l, Al2O3 1.03g / l, effective calcium oxide content in lime 85%;

[0059] Take 3L of alkali wastewater, add 36g of lime and stir for 30 minutes, then separate the solid and liquid and test the supernatant: NaOH 17.8g / lF 0.12g / l, P 1PPM;

[0060] Take 1L of rare earth material solution to be adjusted and use 50% liquid caustic soda to adjust the value, consuming 81.6g of 50% liquid caustic soda;

[0061] Take 240ml of unadjusted rare earth liquid and place it in a 3000ml beaker, add 2.3L of regenerated alkali after F removal to completely precipitate the rare earth, add flocculant to precipitate and filter to obtain alkali cake;

[0062] Take 400 ml of unadjusted rare earth liquid and add alkali cake to adjust the slurry to obtain adjusted slurry;

[0063] The adjusted slurry was transferred to the remaining rare earth liquid to be adjusted, stirred at 50°C for 25 minutes, and the endpoint pH was 4.5;

[0064] Solid-liquid separation:

[0065] Neutralizing solution: REO 205g / l, Fe2O3 0.008g / l; Al2O3 0.013g / l;

[0066] Adjusted slag: REO 0.35%.

[0067] Test Example 3

[0068] like Figure 1As shown, alkali wastewater: NaOH 12.15g / l, F 8.68g / l, P 3g / l; rare earth liquid H + 20g / l, REO213g / l, Fe2O3 12g / l, Al2O3 1.03g / l; effective calcium oxide content in lime is 85%;

[0069] Take 3L of alkali wastewater, add 85g of lime and stir for 30 minutes, then separate the solid and liquid and test the supernatant: NaOH 37g / lF 0.16g / l, P 1PPM;

[0070] Take 1L of rare earth material solution to be adjusted and use 50% liquid caustic soda to adjust the value, consuming 81.6g of 50% liquid caustic soda;

[0071] Take 240ml of unadjusted rare earth liquid and place it in a 3000ml beaker, add 1.1L of F-removing regenerated alkali to wastewater to completely precipitate the rare earth, pour out the supernatant and add 500ML of clean water to wash once, add flocculant to precipitate and filter to obtain alkali cake.

[0072] Take 250 ml of unadjusted rare earth liquid, add alkali cake to adjust the slurry, and obtain adjusted slurry;

[0073] The adjusted slurry was transferred to the remaining rare earth liquid to be adjusted, stirred at 35°C for 35 minutes, and the endpoint pH was 4.5;

[0074] Solid-liquid separation:

[0075] Neutralizing solution: REO 208g / l, Fe2O3 0.009g / l, Al2O3 0.009g / l;

[0076] Adjusted slag: REO 0.45%.

[0077] Test Example 4

[0078] like Figure 1 As shown, alkali wastewater: NaOH 12.15g / l, F 8.68g / l, P 3g / l; rare earth liquid H + 10g / l, REO218g / l, Fe2O3 1.05g / l, Al2O3 0.2g / l; effective calcium oxide content in lime is 85%;

[0079] Take 3L of alkali wastewater, add 95g of lime and stir for 30 minutes, then separate the solid and liquid to detect the supernatant NaOH 36.5g / l, F 0.14g / l, P 1PPM;

[0080] Take 1L of rare earth material solution to be adjusted and use 50% liquid caustic soda to adjust the value, consuming 26.2g of 50% liquid caustic soda;

[0081] Take 84ml of unadjusted rare earth liquid and place it in a 2000ml beaker, add 0.35L of regenerated alkali after removing F to turn wastewater to completely precipitate the rare earth, pour out the supernatant and add 500ml of clean water to wash once, add flocculant to precipitate and filter to obtain alkali cake;

[0082] Take 150 ml of unadjusted rare earth liquid, add alkali cake to adjust the slurry, and obtain adjusted slurry;

[0083] The adjusted slurry was transferred to the remaining rare earth liquid to be adjusted, stirred at 60°C for 25 minutes, and the end point pH = 4.5;

[0084] Solid-liquid separation:

[0085] Neutralizing solution: REO 225g / l, Fe2O3 0.015g / l, Al2O3 0.015g / l;

[0086] Adjusted slag: REO 0.26%.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A rare earth liquid value adjustment process, characterized in that: The steps include: Step 1, obtaining the required alkaline substance content of the total rare earth solution to be adjusted; Step 2, the alkaline substance is alkali-converted wastewater, and the alkali-converted wastewater with a sodium hydroxide content of 5-20 g / l is taken. The content of sodium hydroxide in the alkali-converted wastewater is the content of the alkaline substance required for the total rare earth feed solution to be adjusted obtained in step 1, and fluorine and phosphorus in the alkali-converted wastewater are removed to obtain a low-concentration alkali solution; Step 3, taking the rare earth liquid a to be adjusted, mixing the rare earth liquid a to be adjusted with a low-concentration alkali solution to obtain a mixed slurry, ensuring that the rare earth in the mixed slurry is completely precipitated, and the pH of the mixed slurry is 7-8 when the rare earth is completely precipitated, and preparing an alkali cake; Step 4, taking the rare earth material liquid b to be adjusted and mixing it with the alkali cake, the liquid-to-solid ratio is 1:1-6:1, and the adjusted slurry is obtained; Step 5, mixing the adjusted slurry with the remaining rare earth liquid c to be adjusted, stirring to react, and separating the solid and liquid to obtain a rare earth neutralized liquid. The pH of the adjusted slurry after mixing with the remaining rare earth liquid c to be adjusted is 4-4.5, and stirring to react at 30-60° C. for 10-40 minutes. The sum of the rare earth liquid a to be adjusted, the rare earth liquid b to be adjusted, and the rare earth liquid c to be adjusted is the total amount of the rare earth liquid to be adjusted.

2. A rare earth liquid value adjustment process according to claim 1, characterized in that: In step 1, 1 L of rare earth solution to be adjusted is taken and adjusted to pH 4.5 to obtain the content of consumed alkaline substances, and the total amount of alkaline substances required for the total rare earth solution to be adjusted is obtained by amplification calculation.

3. A rare earth liquid value adjustment process according to claim 1, characterized in that: In step 2, the contents of fluorine and phosphorus in the alkali-conversion wastewater are detected, and calcium oxide with a mass of 1.1-1.3 times of the mass of fluorine and phosphorus is added to remove the fluorine and phosphorus in the alkali-conversion wastewater.

4. A rare earth liquid value adjustment process according to claim 1, characterized in that: After complete precipitation in step 3, PAM flocculation is used, and alkali cake is prepared after plate and frame filtration.

5. A rare earth liquid value adjustment process according to claim 1, characterized in that: The alkaline substance in step 2 is sodium hydroxide. After complete precipitation in step 3, it needs to be diluted, flocculated, washed and desalted before plate and frame filter pressing to prepare alkaline cake.

6. A rare earth liquid value adjustment process according to claim 1, characterized in that: In step 4, the liquid-to-solid ratio is 2:

1.

7. A rare earth liquid value adjustment process according to claim 1, characterized in that: In step 5, the pH of the adjusted slurry after mixing with the remaining rare earth solution c to be adjusted is 4.2, and the mixture is stirred and reacted at 45° C. for 25 minutes.

8. A rare earth liquid value adjustment process according to claim 1, characterized in that: In step 5, adjusted slag is also obtained, and the pH value of the rare earth neutralization solution is 4-4.5.

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