A purifying agent for treating a lead-containing rare earth solution and a method of use

Abstract

The present application belongs to the technical field of rare earth hydrometallurgy, and particularly relates to a purifying agent for treating a lead-containing rare earth solution and an application method. The purifying agent comprises the following raw materials in parts by weight: a sulfur source 5-30 parts, a magnesium source 3-15 parts, and water 40-95 parts; the sulfur source is any one or a combination of two of sodium dimethyl dithiocarbamate and sodium diethyl dithiocarbamate, and sodium pentathiocarbonates; the magnesium source is any one of magnesium chloride, magnesium sulfate, and magnesium nitrate. The present application improves the temperature and acidity application range of the purifying agent, reduces the cooling and neutralization cost of the rare earth solution, utilizes the insolubility of the purifying agent to avoid the residue of excessive purifying agent in the rare earth solution, forms a magnesium polysulfide carbonate salt, improves the ability of magnesium to replace lead ions, and ensures that the lead content in the rare earth solution is removed to a qualified level.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of rare earth hydrometallurgy, and particularly relates to a purifying agent for treating a lead-containing rare earth solution and an application method. BACKGROUND

[0002] In the "concentrate oxidation roasting-hydrochloric acid selective leaching-normal pressure alkali conversion-hydrochloric acid selective dissolution-impurity removal and concentration-extraction separation" smelting process of fluorocarbon cerium ore, impurity elements such as Fe, F, Al, Pb and Ba enter the rare earth solution. In order to ensure the quality of rare earth products, impurities in the rare earth solution must be removed. In the current process, after the rare earth solution is subjected to Fe, F and Al removal and concentration operations, the REO concentration in the solution is 200-350 g / L, and the PbO concentration is as high as 1-3 g / L.

[0003] The traditional lead removal method is sulfidation lead removal, that is, a sulfidation agent such as sodium sulfide or ammonium sulfide is added to the rare earth solution to form lead sulfide precipitation, so that the mass concentration ratio of PbO / REO in the solution is less than 0.01%. This method has obvious defects, mainly including: ① The sulfidation agent is usually strongly alkaline, causing a large amount of loss of rare earth hydroxide, with a loss rate of 1%-2%; ② The sulfidation agent is prone to hydrolysis to generate highly toxic hydrogen sulfide gas, causing serious production safety risks; ③ A large amount of lead slag with high rare earth content is generated, which needs to be further recovered, increasing the production process and cost. Other lead removal methods include electrochemical method, ion exchange method, extraction method, etc., but because of high operating cost, strict process conditions and unstable effect, they have not been widely used in industry.

[0004] With the increasing strictness of environmental protection requirements, wastewater lead removal is also a research hotspot. The composition of wastewater is relatively simple and generally does not contain high-concentration metal elements, reducing the difficulty of lead removal. At present, the common lead removal agent in the field of wastewater lead removal is sodium dimethyl dithiocarbamate, but there is no relevant application report on its use in impurity removal of high-concentration rare earth solution. Preliminary research shows that the application of sodium dimethyl dithiocarbamate in rare earth solution lead removal can achieve selective lead removal, reduce the loss rate of rare earth in the lead removal process, and does not generate highly toxic hydrogen sulfide gas. However, because sodium dimethyl dithiocarbamate is prone to decomposition under high temperature and high acidity conditions, the lead removal effect is poor, and therefore there is a disadvantage of low temperature and acidity (temperature ≤ 60 ℃, pH value ≥ 2), which limits the application of sodium dimethyl dithiocarbamate in rare earth solution lead removal.

[0005] Therefore, it is of great significance to develop a lead removal purifying agent and application method, reduce the loss of rare earth in the lead removal process of rare earth solution and safety risks, and improve the temperature and acidity use conditions of the purifying agent, for improving the level of rare earth smelting technology in China. SUMMARY

[0006] The present application aims at the problems existing in the prior art, and provides a purifying agent for treating a lead-containing rare earth solution.

[0007] In order to achieve the above-mentioned purpose, the specific technical scheme of the present application is as follows:

[0008] The purifying agent for treating a lead-containing rare earth solution comprises the following raw materials by weight: 5-30 parts (specifically 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, etc.) of a sulfur source, 3-15 parts (specifically 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, etc.) of a magnesium source, and 40-95 parts (specifically 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, 90 parts, 95 parts, etc.) of water; the sulfur source is any one or a combination of dimethyl dithiocarbamic acid sodium and diethyl dithiocarbamic acid sodium (i.e. a combination of dimethyl dithiocarbamic acid sodium and sodium pentathiocarbonate; or a combination of diethyl dithiocarbamic acid sodium and sodium pentathiocarbonate; or a combination of dimethyl dithiocarbamic acid sodium, diethyl dithiocarbamic acid sodium and sodium pentathiocarbonate); and the magnesium source is any one of magnesium chloride, magnesium sulfate and magnesium nitrate.

[0009] As a preferred embodiment in the present application, the preparation method of the purifying agent for treating a lead-containing rare earth solution comprises the following steps:

[0010] The raw materials are weighed in proportion and stirred to mix uniformly, and a suspension is obtained by reaction; the suspension is filtered to obtain filter residue; and the filter residue is dried to constant weight to obtain a lead removal purifying agent.

[0011] Preferably, in the above method, the stirring reaction temperature is 10-50℃ (specifically 10℃, 15℃, 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, etc.), and the time is 5-30 minutes (specifically 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, etc.).

[0012] Preferably, in the above method, the filter residue is dried at a temperature of 45-55℃ (specifically 45℃, 46℃, 47℃, 48℃, 49℃, 50℃, 51℃, 52℃, 53℃, 54℃, 55℃, etc.).

[0013] As a preferred embodiment in the present application, the purifying agent for treating the lead-containing rare earth solution obtained by the above method is used in the method for treating the lead-containing rare earth solution, which comprises the following steps:

[0014] S1) adding the lead-containing rare earth solution into a stirring tank;

[0015] S2) uniformly adding the lead-removing purifying agent into the lead-containing rare earth solution, controlling the mass ratio of the added lead-removing purifying agent to the PbO contained in the lead-containing rare earth solution as W, stirring and carrying out the lead-removing reaction;

[0016] S3) solid-liquid separation, obtaining a low-lead rare earth solution and a lead residue, washing and drying the lead residue, and analyzing the composition of the low-lead rare earth solution and the lead residue.

[0017] As preferred, the concentration of the rare earth oxide REO in the lead-containing rare earth solution in S1) is 200-350 g / L (specifically, 200 g / L, 210 g / L, 220 g / L, 230 g / L, 240 g / L, 250 g / L, 260 g / L, 270 g / L, 280 g / L, 290 g / L, 300 g / L, 310 g / L, 320 g / L, 320 g / L, 340 g / L, 350 g / L, etc.), and the concentration of hydrogen ions is 0.01-0.2 mol / L (specifically, 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, etc.).

[0018] As preferred, W in S2) is 2.8-5.0 (specifically, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, 5.0, etc.), and more preferably, W is 3.5-4.4.

[0019] As preferred, the temperature of the lead-removing reaction in S2) is 60-100 ℃ (specifically, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃, 95 ℃, 100 ℃, etc.), and the time is 60-180 minutes (specifically, 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes, 120 minutes, 130 minutes, 140 minutes, 150 minutes, 160 minutes, 170 minutes, 180 minutes, etc.).

[0020] As preferred, the mass concentration ratio of PbO to REO in the low-lead rare earth solution in S3) is <0.01%, and the REO content in the lead residue is <2 wt%.

[0021] Compared with the prior art, the present application has the following positive effects:

[0022] (i) This application solves the problem of high rare earth loss rate in traditional processes. In this application, the lead removal purifying agent is not easily soluble, and the purifying agent undergoes a solid-liquid exchange reaction with the solution. That is, the magnesium element in the purifying agent preferentially replaces the lead ions in the rare earth solution without reacting with the rare earth ions, thereby achieving selective lead removal and reducing the rare earth loss rate in the lead removal process. This avoids the generation of rare earth-containing lead slag and also avoids the adverse effects of residual rare earth in the rare earth solution on subsequent extraction, wastewater treatment processes, and product quality.

[0023] (ii) Reduced safety risks in the lead removal process. The sulfur and carbon elements in the lead removal purifier form relatively stable carbon-sulfur bonds, and do not hydrolyze to generate highly toxic hydrogen sulfide gas during use.

[0024] (III) Compared with directly using sodium dimethyl dithiocarbamate or sodium diethyl dithiocarbamate for lead removal from rare earth solutions, this invention prepares a lead removal purifier containing polythiocarbamate magnesium salts that is not easily dissolved by reacting a sulfur source with a magnesium source. This purifier is not easily decomposed under high temperature and high acidity conditions, thereby solving the following technical problems:

[0025] (1) The temperature range for lead removal has been increased. The applicable temperature has been increased from 20-60℃ to 60-100℃, thereby reducing the cooling process of rare earth concentrate during production, shortening the production cycle, and reducing equipment investment;

[0026] (2) The acidity conditions for lead removal have been improved. The applicable acidity has been reduced from pH ≥ 2 to 0.01–0.2 mol / L hydrogen ion concentration, thereby avoiding the neutralization process of high-acidity rare earth solutions;

[0027] (3) It avoids the adverse effects of residual lead-removing purifying agent in the rare earth solution on subsequent extraction, wastewater treatment processes, and product quality. Because lead-removing purifying agent is not easily soluble, excess lead-removing purifying agent will remain in the residue and separate from the rare earth solution;

[0028] (4) Polythiocarbamate magnesium salt is formed. Compared with purifiers without sodium pentathiocarbamate, the purifier in this invention has a stronger ability to replace lead ions with magnesium, thereby ensuring that the lead content in the rare earth solution is removed to the acceptable level. Detailed Implementation

[0029] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0030] Any feature disclosed in this specification (including the claims and abstract) may be replaced by other equivalent or similar features, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.

[0031] Example 1:

[0032] Add 20g sodium dimethyl dithiocarbamate, 30g sodium pentathiocarbonate, 150g magnesium chloride, and 800mL water to a beaker and stir until homogeneous. Maintain the mixture in a water bath at 10°C and continue stirring for 5 minutes to stop the reaction. Filter the slurry, and dry the resulting residue at 50°C to constant weight; this is the lead removal purifier (custom code CQJ-1).

[0033] Take 1L of lead-rare earth solution with REO concentration of 205.38g / L and PbO concentration of 0.966g / L. Adjust the hydrogen ion concentration to 0.01mol / L using hydrochloric acid. Heat the solution in a water bath to 60℃, add 2.70g of CQJ-1 evenly, and stir for 60 minutes.

[0034] After solid-liquid separation, a low-lead rare earth solution and lead slag were obtained. The lead slag was then washed and dried. Analysis showed that the PbO / REO mass concentration ratio in the low-lead rare earth solution was 0.035%, the REO content in the lead slag was 0.94 wt%, and the praseodymium-neodymium oxide loss rate during the lead removal process was 0.01%.

[0035] Example 2:

[0036] In this embodiment, the synthesis conditions of the lead-removing purifier are the same as in Example 1.

[0037] Take 1 L of lead-rare earth solution with REO concentration of 205.38 g / L and PbO concentration of 0.966 g / L. Adjust the hydrogen ion concentration to 0.15 mol / L using hydrochloric acid. Heat the solution in a water bath to 60 °C, add 3.38 g of CQJ-1 evenly, and stir for 60 minutes. The results are shown in Table 1.

[0038] Example 3:

[0039] Add 30g sodium diethyldithiocarbamate, 20g sodium pentathiocarbonate, 30g magnesium chloride, and 920mL water to a beaker and stir until homogeneous. Maintain the mixture in a water bath at 25°C and continue stirring for 20 minutes to stop the reaction. Filter the slurry, and dry the resulting residue at 50°C to constant weight; this is the lead removal purifier (custom code CQJ-3).

[0040] Take 1 L of lead-rare earth solution with REO concentration of 294.10 g / L and PbO concentration of 1.574 g / L. Adjust the hydrogen ion concentration to 0.12 mol / L using hydrochloric acid. Heat the solution in a water bath to 70 °C, add 5.51 g of CQJ-3 evenly, and stir for 100 minutes. The results are shown in Table 1.

[0041] Example 4:

[0042] Add 100g sodium dimethyl dithiocarbamate, 50g sodium diethyl dithiocarbamate, 50g sodium pentathiocarbonate, 150g magnesium sulfate, and 650mL water to a beaker and stir until homogeneous. Maintain the mixture in a water bath at 40℃ and continue stirring for 20 minutes to stop the reaction. Filter the slurry, and dry the resulting residue at 50℃ to a constant weight; this is the lead removal purifying agent (custom code CQJ-4).

[0043] Take 1 L of lead-rare earth solution with REO concentration of 344.06 g / L and PbO concentration of 1.700 g / L. Adjust the hydrogen ion concentration to 0.20 mol / L using hydrochloric acid. Heat the solution in a water bath to 90 °C, add 7.48 g of CQJ-4 evenly, and stir for 140 minutes. The results are shown in Table 1.

[0044] Example 5:

[0045] Add 150g sodium dimethyl dithiocarbamate, 20g sodium diethyl dithiocarbamate, 130g sodium pentathiocarbonate, 100g magnesium nitrate, and 600mL water to a beaker and stir until homogeneous. Maintain the mixture in a water bath at 50°C and continue stirring for 30 minutes to stop the reaction. Filter the slurry, and dry the resulting residue at 50°C to constant weight; this is the lead removal purifying agent (custom code CQJ-5).

[0046] Take 1 L of lead-rare earth solution with REO concentration of 344.06 g / L and PbO concentration of 1.700 g / L. Adjust the hydrogen ion concentration to 0.20 mol / L using hydrochloric acid. Heat the solution in a water bath to 100 °C, add 8.50 g of CQJ-5 evenly, and stir for 180 minutes. The results are shown in Table 1.

[0047] Example 6:

[0048] In this embodiment, the synthesis conditions of the lead-removing purifier are the same as in Example 5.

[0049] Take 1 L of lead-rare earth solution with REO concentration of 344.06 g / L and PbO concentration of 1.700 g / L. Adjust the hydrogen ion concentration to 0.01 mol / L using hydrochloric acid. Heat the solution in a water bath to 90 °C, add 7.48 g of CQJ-5 evenly, and stir for 100 minutes. The results are shown in Table 1.

[0050] As can be seen from the results of Examples 1 to 6, when using the lead removal purifier of the present invention at a lead removal temperature of 60 to 100°C and a mass ratio of lead removal agent to PbO contained in the lead-containing rare earth solution of 3.5 to 5.0, the PbO / REO in the rare earth solution can be reduced to <0.01%, the lead content is qualified, and the praseodymium-neodymium loss rate is ≤0.03%.

[0051] Comparative Example 1:

[0052] Take 1 L of lead-rare earth solution with REO concentration of 344.06 g / L and PbO concentration of 1.700 g / L. Adjust the hydrogen ion concentration to 0.01 mol / L using hydrochloric acid. Heat the solution in a water bath to 90 °C, and uniformly add 74.8 mL of 100 g / L sodium dimethyl dithiocarbamate. Stir the reaction for 100 minutes. The results are shown in Table 2.

[0053] Comparative Example 2:

[0054] Take 1 L of lead-rare earth solution with REO concentration of 205.38 g / L and PbO concentration of 0.966 g / L. Adjust the hydrogen ion concentration to 0.15 mol / L using hydrochloric acid. Heat the solution in a water bath to 60 °C, and uniformly add 33.8 mL of 100 g / L sodium dimethyl dithiocarbamate. Stir the reaction for 60 minutes. The results are shown in Table 2.

[0055] Comparative Example 3:

[0056] In this embodiment, 74.8 mL of 100 g / L sodium diethyldithiocarbamate was added to remove lead from the rare earth solution, and other conditions were the same as in Comparative Example 1. The results are listed in Table 2.

[0057] Comparative Example 4:

[0058] In this embodiment, 33.8 mL of 100 g / L sodium diethyldithiocarbamate was added to remove lead from the rare earth solution, and other conditions were the same as in Comparative Example 2. The results are listed in Table 2.

[0059] Comparative Example 5:

[0060] In this embodiment, 74.8 mL of 100 g / L sodium pentathiocarbonate was added to remove lead from the rare earth solution, and other conditions were the same as in Comparative Example 1. The results are listed in Table 2.

[0061] Comparative Example 6:

[0062] In this embodiment, 33.8 mL of 100 g / L sodium pentathiocarbonate was added to remove lead from the rare earth solution, and other conditions were the same as in Comparative Example 2. The results are listed in Table 2.

[0063] Comparative Example 7:

[0064] In this embodiment, 74.8 mL of 100 g / L magnesium chloride was added to remove lead from the rare earth solution, and other conditions were the same as in Comparative Example 1. The results are listed in Table 2.

[0065] Comparative Example 8:

[0066] 5.61 g of industrial sodium sulfide, 1.87 g of magnesium nitrate, and 11.3 mL of water were added to a beaker and stirred until a suspension was prepared. The suspension was then subjected to rare earth solution treatment for lead removal, under the same conditions as Comparative Example 1. The results are shown in Table 2.

[0067] Table 1

[0068]

[0069] Table 2

[0070]

[0071] A comparison of Tables 1 and 2 shows that, based on the results of Comparative Examples 1-7, using any one of the following reagents alone for lead removal—sodium dimethyl dithiocarbamate, sodium diethyl dithiocarbamate, sodium pentathiocarbonate, and magnesium chloride—results in poor lead removal efficiency under high temperature or high acidity conditions, failing to meet the lead removal requirements of rare earth solutions. Comparative Example 8 indicates that the reagent prepared from industrial sodium sulfide and magnesium nitrate exhibits a high rare earth loss rate during lead removal, failing to simultaneously remove lead from the rare earth solution to acceptable levels and reduce rare earth loss in the lead slag.

[0072] The examples described above are merely preferred embodiments of this patent, but the scope of protection of this patent is not limited thereto. It should be noted that, for those skilled in the art, without departing from the principles of this patent, based on the technical solution and patent concept of this patent, several improvements and modifications can be made, and these improvements and modifications should also be considered within the scope of protection of this patent.

Claims

1. A purifying agent for treating lead-containing rare earth solutions, characterized in that... This purifying agent is used to treat lead-containing rare earth solutions. The purifying agent is composed of the following raw materials in parts by weight: 5-30 parts sulfur source, 3-15 parts magnesium source, and 40-95 parts water. The sulfur source is any one or a combination of sodium dimethyl dithiocarbamate, sodium diethyl dithiocarbamate, and sodium pentathiocarbonate. The magnesium source is any one of magnesium chloride, magnesium sulfate, and magnesium nitrate. During preparation, the raw materials are weighed according to the specified proportions and stirred until uniformly mixed, reacting to obtain a suspension. The suspension is then filtered to obtain a filter residue. Finally, the residue is dried to a constant weight to obtain the lead-removing purifying agent.

2. The method for preparing the purifying agent for treating lead-containing rare earth solutions as described in claim 1, characterized in that... Includes the following steps: Weigh each raw material according to the proportion, stir to mix them evenly, and react to obtain a suspension; filter the suspension to obtain filter residue; dry the residue to constant weight to obtain lead removal and purification agent.

3. The method for preparing the purifying agent for treating lead-containing rare earth solutions as described in claim 2, characterized in that: The stirring reaction temperature is 10~50℃, and the time is 5~30 minutes.

4. The method for preparing the purifying agent for treating lead-containing rare earth solutions as described in claim 2, characterized in that: The drying temperature of the filter residue is 45~55℃.

5. A method for treating lead-containing rare earth solutions using the purification agent obtained by the preparation method according to any one of claims 2-4, characterized in that... Includes the following steps: S1) Add the lead-containing rare earth solution to the mixing tank; S2) Add the lead-removing purifier evenly to the lead-containing rare earth solution, and control the mass ratio of the added lead-removing purifier to the PbO contained in the lead-containing rare earth solution to be W. Stir and carry out the lead removal reaction. S3) Solid-liquid separation was performed to obtain a low-lead rare earth solution and lead slag. The lead slag was washed and dried, and the composition of the low-lead rare earth solution and lead slag was analyzed.

6. The method for treating lead-containing rare earth solutions as described in claim 5, characterized in that: The concentration of rare earth oxides (REO) in the lead-containing rare earth solution (S1) is 200~350 g / L, and the concentration of hydrogen ions is 0.01~0.2 mol / L.

7. The method for treating lead-containing rare earth solutions as described in claim 5, characterized in that: In S2), W is 2.8~5.

0.

8. The method for treating lead-containing rare earth solutions as described in claim 5, characterized in that: The lead removal reaction temperature in S2 is 60~100℃, and the time is 60~180 minutes.

9. The method for treating lead-containing rare earth solutions as described in claim 5, characterized in that: In S3, the mass concentration ratio of PbO to REO in low-lead rare earth feed solution is <0.01%; the REO content in lead slag is <2wt%.

10. The method for treating lead-containing rare earth solutions as described in claim 7, characterized in that: W is 3.5~4.4.

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