Method for preparing low-sulfate rare earth carbonate by using mixed precipitator

Abstract

The invention provides a method for preparing low-sulfate rare earth carbonate by using a mixed precipitator, and belongs to the technical field of hydrometallurgy. According to the method provided by the invention, after a sulfuric acid rare earth solution and a mixed precipitator solution are added in a parallel flow manner, a heat preservation reaction is performed. The mixed precipitant is used for precipitation, the alkalinity of the precipitant is improved, and carbon emission and wastewater amount in the precipitation process are effectively reduced. The method solves the problem of high content of sulfate radical impurities in the conversion process of rare earth chloride by a mixed sulfuric acid rare earth feed liquid ammonium bicarbonate precipitation method, and solves the problem of high cost caused by adoption of a related organic extraction agent in the conversion process of an extraction method. In the obtained rare earth carbonate, the REO content is 50-65%, and the sulfate radical content is 1t; and 0.01% of the total weight.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy, and in particular to a method for preparing low-sulfate rare earth carbonate by using a mixed precipitant. Background Art

[0002] The decomposition of rare earth concentrates is mostly carried out by high-temperature roasting with concentrated sulfuric acid. After high-temperature roasting, a mixed rare earth sulfate solution is obtained. The roasted ore is subjected to a water leaching and impurity removal process to obtain a rare earth sulfate water extract. The water extract is converted into an ammonium salt to obtain a mixed rare earth carbonate. However, the mixed rare earth carbonate precipitated in the sulfuric acid system contains a high content of SO4 2- Therefore, the impurity SO4 in the rare earth chloride solution obtained after dissolving with concentrated hydrochloric acid 2- Higher.

[0003] Patent publication number CN111020240A describes a method and device for continuously preparing mixed rare earth chloride feed solution from rare earth sulfate solution. The invention can realize the continuous production of mixed rare earth chloride feed solution from rare earth sulfate water leaching solution by involving special devices, realize the continuous precipitation of rare earth sulfate solution to obtain rare earth carbonate, improve equipment utilization, and improve the degree of automation of production, but it does not take into account the reduction of SO4 in this process. 2- The content.

[0004] Patent publication number CN101798627A describes a new method for precipitating rare earths, which uses calcium or / and magnesium minerals as raw materials and pure magnesium bicarbonate and / or calcium bicarbonate aqueous solution prepared by calcination-digestion-carbonization as precipitants to precipitate rare earths. Although the invention uses magnesium bicarbonate to reduce the carbon precipitation cost, it does not take into account the SO4 2- The content. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a method for preparing low-sulfate rare earth carbonate using a mixed precipitant. The method provided by the present invention can significantly reduce the sulfate content in the obtained rare earth carbonate to a content of <0.01%.

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

[0007] One of the technical solutions of the present invention is a method for preparing low-sulfate rare earth carbonate using a mixed precipitant, which comprises adding a rare earth sulfate solution and a mixed precipitant solution in a parallel flow manner and then performing a heat-insulating reaction.

[0008] The second technical solution of the present invention is a method for reducing the sulfate content in rare earth sulfate, and preparing low-sulfate rare earth carbonate using the method described in the above technical solution.

[0009] The present invention discloses the following technical effects:

[0010] The present invention uses a mixed precipitant for precipitation, thereby increasing the alkalinity of the precipitant and effectively reducing carbon emissions and wastewater volume during the precipitation process.

[0011] The invention solves the problem of high sulfate impurities in the process of transforming mixed sulfuric acid rare earth feed liquid into rare earth chloride by ammonium bicarbonate precipitation method, and solves the problem of high cost of using relevant organic extractants in the process of transformation by extraction method.

[0012] The raw materials used in the invention have low cost, low energy consumption at room temperature, simple operation, and are easy to scale up for industrial production.

[0013] The product obtained by the invention has high quality, is convenient for product transportation, and reduces transportation costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 This is a SEM image of the low-sulfate rare earth carbonate prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0016] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0017] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0018] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0019] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0020] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0021] The invention provides a method for preparing low-sulfate rare earth carbonate by using a mixed precipitant. A rare earth sulfate solution and a mixed precipitant solution are added in a parallel flow manner and then a heat preservation reaction is carried out.

[0022] In the present invention, when the pH value of the reaction system is 5.2, precipitation begins to be produced. When the reactor is full, the product rare earth carbonate is separated. When separating the precipitate (i.e., the product sulfate rare earth carbonate), the rare earth sulfate solution and the mixed precipitant solution are kept in parallel flow and fed to achieve continuous production.

[0023] In some embodiments of the present invention, the present invention adopts a parallel flow method to add a rare earth sulfate solution and a mixed precipitant solution into a reactor for heat preservation reaction; water is pre-added into the reactor as a bottom liquid. The present invention has no special requirements for the reactor, and a reactor familiar to those skilled in the art can be selected.

[0024] In some embodiments of the present invention, the rare earth sulfate solution is a single rare earth sulfate solution or a mixed rare earth sulfate solution; the concentration of the rare earth sulfate solution is 1-45 g / L in terms of REO.

[0025] In some embodiments of the present invention, HCO3 in the mixed precipitant solution - With OH - The molar ratio is 1:(0.43-1); the concentration of the mixed precipitant solution is 1-4.0 mol / L.

[0026] In the present invention, if HCO3 - If the content is too low, the volume of the supernatant will increase, increasing the amount of wastewater. - If the content is too high, the local reaction will be too intense, and the amount of sulfate ions will increase. If the concentration of the mixed precipitant is too low, the amount of wastewater will increase. If the concentration is too high, the product will produce rare earth hydroxide.

[0027] In some embodiments of the present invention, the mixed precipitant is two of ammonium bicarbonate, ammonia water, sodium bicarbonate, sodium hydroxide, ammonium carbonate and sodium carbonate, and the mixed precipitant also contains HCO3 - and OH- .

[0028] In some embodiments of the present invention, the mixed precipitant is ammonium bicarbonate and ammonia water, sodium bicarbonate and sodium hydroxide, ammonium bicarbonate and ammonium carbonate, or sodium bicarbonate and sodium carbonate.

[0029] In some embodiments of the present invention, the flow rate of the mixed precipitant solution is: the time for the reactor to be filled with liquid is controlled to be greater than or equal to 2 hours and less than or equal to 8 hours, and the feeding rate is maintained at a uniform rate; the relative flow rate ratio of the rare earth sulfate solution to the mixed precipitant solution is 1:(2.8-3).

[0030] In the present invention, the present invention controls the flow rate of the feed by controlling the feeding time of each batch of materials, and maintains a uniform feeding speed during feeding. In actual operation, when feeding for the first time, the feed liquid in the reactor is filled from empty to full, and the time for controlling the liquid in the reactor to be filled is greater than or equal to 2h and less than or equal to 8h, and the flow rate is kept to feed at a uniform speed; in the subsequent continuous production process, the flow rate is kept to feed at a uniform speed. If the flow rate is too fast, the reaction is insufficient, the crystal particles are small, and it is not easy to filter; if the reaction is too slow and wastes time, for economic benefits, the present invention preferably has the flow rate as the above parameters.

[0031] In the present invention, if the flow rate ratio of the rare earth sulfate solution to the mixed precipitant solution is too low or too high, the chloride ion in the product will increase. Therefore, the preferred flow rate ratio of the present invention is within the above parameter range.

[0032] In some embodiments of the present invention, the temperature of the insulation reaction is 30-70°C.

[0033] In some embodiments of the present invention, the heat preservation reaction process also includes stirring.

[0034] In some embodiments of the present invention, after the heat preservation reaction is completed, the steps of dynamic aging, filtering, and washing the filtered sample are also included.

[0035] The present invention controls the concentration, relative flow rate, flow rate and other factors of rare earth sulfate solution and mixed precipitant solution to control RE in the reaction system. 3+ With CO3 2- The molar ratio (1:(3-3.6)) and the pH value of the reaction system (5.6-6.2) can obtain low sulfate rare earth carbonate, wherein the total rare earth (REO) content is greater than 50wt%, SO4 2- Content <0.01wt%, particle size D of low sulfate rare earth carbonate 50 50-70μm.

[0036] The present invention also provides a method for reducing the sulfate content in rare earth sulfate, and the method described in the above technical solution is used to prepare low-sulfate rare earth carbonate.

[0037] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0038] Unless otherwise specified, the raw materials and reagents used in the examples can be obtained through commercial channels.

[0039] Example 1

[0040] Take 1L of sulfuric acid mixed rare earth feed liquid as the reaction raw material, wherein the rare earth concentration is 42g / L (in terms of REO); prepare 2L of mixed precipitant, whose concentration is 3.8mol / L (mixed precipitant is prepared by ammonium bicarbonate and ammonia water in a molar ratio of 1:0.8). Add the above two solutions to the reactor by co-current dropwise addition for reaction. The volume of the reactor is 5L. The time for the reactor to be filled with the feed liquid is controlled to be 6.25h. The relative flow rate ratio of the sulfuric acid rare earth feed liquid and the mixed precipitant is 1:2.8. Deionized water is pre-added in the reactor as the bottom liquid; the reaction temperature is 60℃; and stirring is continued during the reaction. After the feeding is completed, stir for 10min, filter, and wash with 0.5L of 90℃ water to obtain a mixed rare earth carbonate solid, wherein the total rare earth content (REO) is 52wt%, the sulfate content is 98ppm, and the particle size D 50 It is 52μm.

[0041] Example 2

[0042] Take 1L of sulfuric acid mixed rare earth feed liquid as the reaction raw material, and its rare earth concentration is 12g / L (in terms of REO); prepare 1L of mixed precipitant, and its concentration is 3.8mol / L (mixed precipitant is prepared by ammonium bicarbonate and sodium hydroxide with a molar ratio of 1:0.8). The above two solutions are added to the reactor by parallel flow dropwise addition for reaction. The volume of the reactor is 5L, and the time for the reactor to be filled with the feed liquid is controlled to be 4h. The relative flow rate ratio of the sulfuric acid rare earth feed liquid and the mixed precipitant is 1:2.54. Deionized water is pre-added in the reactor as the bottom liquid; the reaction temperature is 60℃, and stirring is continued during the reaction. After the feeding is completed, stir for 15min, filter, and wash with 0.5L of 90℃ water to obtain a mixed rare earth carbonate solid, wherein the total rare earth content (REO) is 55wt%, the sulfate content is 86ppm, and the particle size D 50 It is 57μm.

[0043] Example 3

[0044] Take 1L of sulfuric acid mixed rare earth feed liquid as the reaction raw material, and its rare earth concentration is 1g / L (in terms of REO); prepare 2L of mixed precipitant, and its concentration is 3.4mol / L (mixed precipitant is prepared by ammonium bicarbonate and ammonia water with a molar ratio of 1:0.6). The above two solutions are added to the reactor by parallel flow dropwise addition for reaction. The volume of the reactor is 5L, and the time for the reactor to be filled with the feed liquid is controlled to be 6h. The relative flow rate ratio of the sulfuric acid rare earth feed liquid and the mixed precipitant is 1:2.73. Deionized water is pre-added in the reactor as the bottom liquid; the reaction temperature is 20℃, and stirring is continued during the reaction. After the feeding is completed, stir for 10min, filter, and wash with 0.5L of 20℃ water to obtain a mixed rare earth carbonate solid, wherein the total rare earth content (REO) is 51wt%, the sulfate content is 99ppm, and the particle size D 50 It is 54μm.

[0045] Example 4

[0046] Take 1L of sulfuric acid mixed rare earth feed liquid as the reaction raw material, and its rare earth concentration is 28g / L (in terms of REO); prepare 2L of mixed precipitant, and its concentration is 2mol / L (mixed precipitant is prepared by ammonium bicarbonate and sodium hydroxide with a molar ratio of 1:0.4). The above two solutions are added to the reactor by parallel flow dropwise addition for reaction. The volume of the reactor is 5L, and the time for the reactor to be filled with the feed liquid is controlled to be 4h. The relative flow rate ratio of the sulfuric acid rare earth feed liquid and the mixed precipitant is 1:2.68. Deionized water is pre-added in the reactor as the bottom liquid; the reaction temperature is 30℃, and stirring is continued during the reaction. After the feeding is completed, stir for 10min, filter, and wash with 0.5L of 30℃ water to obtain a mixed rare earth carbonate solid, wherein the total rare earth content (REO) is 51%, the sulfate content is 78ppm, and the particle size D 50 It is 66μm.

[0047] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing low-sulfate rare earth carbonate using a mixed precipitant, characterized in that: After adding the rare earth sulfate solution and the mixed precipitant solution in a parallel flow manner, a heat preservation reaction is carried out.

2. The method for preparing low-sulfate rare earth carbonate using a mixed precipitant according to claim 1, characterized in that: The rare earth sulfate solution is a single rare earth sulfate solution or a mixed rare earth sulfate solution; the concentration of the rare earth sulfate solution is 1-45 g / L in terms of REO.

3. The method for preparing low-sulfate rare earth carbonate using a mixed precipitant according to claim 1, characterized in that: The mixed precipitant solution contains HCO3 - With OH - The molar ratio is 1:(0.43-1); the concentration of the mixed precipitant solution is 1-4.0 mol / L.

4. The method for preparing low-sulfate rare earth carbonate using a mixed precipitant according to claim 3, characterized in that: The mixed precipitant is two of ammonium bicarbonate, ammonia water, sodium bicarbonate, sodium hydroxide, ammonium carbonate and sodium carbonate, and the mixed precipitant also contains HCO3 - and OH - .

5. The method for preparing low-sulfate rare earth carbonate using a mixed precipitant according to claim 1, characterized in that: The flow rate of the mixed precipitant solution is: the time for the reactor to be filled with liquid is controlled to be greater than or equal to 2 hours and less than or equal to 8 hours, and the feeding speed is maintained at a uniform rate; the relative flow rate ratio of the rare earth sulfate solution to the mixed precipitant solution is 1:(2.8-3).

6. The method for preparing low-sulfate rare earth carbonate using a mixed precipitant according to claim 1, characterized in that: The temperature of the heat preservation reaction is 30-70°C.

7. The method for preparing low-sulfate rare earth carbonate using a mixed precipitant according to claim 1, characterized in that: The heat preservation reaction process also includes stirring.

8. The method for preparing low-sulfate rare earth carbonate using a mixed precipitant according to claim 1, characterized in that: After the heat preservation reaction is completed, the steps of dynamic aging, filtering, and washing the filtered sample are also included.

9. A method for reducing the sulfate content in rare earth sulfate, characterized in that: The method according to any one of claims 1 to 8 is used to prepare low-sulfate rare earth carbonate.

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