阅读说明：本技术 一种降低稀土金属熔盐渣产生量的电解方法 (Electrolysis method for reducing generation amount of rare earth metal molten salt slag ) 是由 王金镛 朱玉彬 李东明 赵海罗 于 2021-10-29 设计创作，主要内容包括：本发明公开了一种降低稀土金属熔盐渣产生量的电解方法,根据稀土氧化物的物理性状,调节熔盐电解质的粘度和电导率,再采用的相应的电流电压进行电解。本发明通过该方法加入炉内的稀土氧化物料都被电解成为稀土金属,减少了电解过程熔盐渣的产生量,在加入同样多原料的情况下,得到了更多的稀土金属,一方面提高了稀土金属的电解回收率,另一方面也提高了一次电解的产力。(The invention discloses an electrolysis method for reducing the generation amount of rare earth metal molten salt slag, which adjusts the viscosity and the conductivity of molten salt electrolyte according to the physical properties of rare earth oxide and then carries out electrolysis by adopting corresponding current and voltage. The rare earth oxide materials added into the furnace are electrolyzed into rare earth metals by the method, so that the production amount of molten salt slag in the electrolysis process is reduced, more rare earth metals are obtained under the condition of adding the same amount of raw materials, the electrolysis recovery rate of the rare earth metals is improved on one hand, and the output of one-time electrolysis is also improved on the other hand.)

1. An electrolysis method for reducing the generation amount of rare earth metal molten salt slag is characterized in that the viscosity and the conductivity of molten salt electrolyte are adjusted according to the physical properties of rare earth oxide, and then the rare earth oxide and the molten salt electrolyte are uniformly mixed and then added into an electrolytic furnace for electrolysis.

2. The electrolysis method for reducing the generation of molten salt slag of rare earth metal according to claim 1, wherein the indicator of physical properties includes bulk density or wettability.

3. The electrolysis method for reducing the generation amount of the rare earth metal molten salt slag according to claim 1, wherein the mass ratio of the rare earth oxide to the molten salt electrolyte is 100: 3-7.

4. The electrolysis method for reducing the generation amount of the molten salt slag of the rare earth metal according to claim 3, wherein the molten salt electrolyte consists of rare earth fluoride and lithium fluoride, and the mass ratio of the rare earth fluoride to the lithium fluoride is 6-10: 1.

5. The electrolysis method for reducing the generation amount of the rare earth metal molten salt slag according to claim 3, wherein the rare earth oxide is a light rare earth metal oxide.

6. The electrolysis method for reducing the generation amount of the rare earth metal molten salt slag according to claim 3, wherein the rare earth fluoride is a light rare earth metal fluoride.

7. The electrolysis method for reducing the generation amount of the rare earth metal molten salt slag according to claim 1, wherein the electrolysis voltage is 3-4 times of the theoretical decomposition voltage of the rare earth metal oxide.

Technical Field

The invention belongs to the technical field of rare earth metal electrolysis, and particularly relates to an electrolysis method for reducing the generation amount of rare earth metal molten salt slag.

Background

The existing rare earth metal production mostly adopts an oxide-fluoride molten salt electrolysis mode, namely rare earth oxide is taken as a main raw material, fluoride is taken as molten salt electrolyte, and under the high temperature state, Rare Earth Oxide (REO) is dissolved in the molten salt electrolyte and is decomposed into rare earth metal ions (RE) with positive charge³⁺) And negatively charged oxygen ions (O)^2-) Positively charged rare earth metal ions (RE) under the action of a DC electric field³⁺) Migrate to the cathode and obtain electrons at the cathode to become rare earth metal (RE); negatively charged oxygen ion (O)^2-) Migrate to the anode and release electrons at the anode to become molecular oxygen (O)₂) Moiety (II)The oxygen molecules react with the carbon in the graphite anode to produce carbon dioxide (CO)₂)。

The rare earth oxides used for electrolysis have wide sources, although the chemical compositions of the rare earth oxides are not greatly different, the physical indexes (such as the granularity of raw materials, the bulk density, the fluidity, the infiltration performance and the like in a loose state and a compacted state) of the rare earth oxides are greatly different, so that the electrolysis reaction effect of the raw materials of different manufacturers added into the electrolytic furnace is greatly different, some raw materials added into the furnace float on the surface of electrolyte liquid and are not easily infiltrated by the electrolyte, and the flying loss is increased due to the driving of hot air flow; some raw materials are added into the furnace to be deposited quickly and sink to the bottom of the furnace without sufficient reaction, and are gathered with impurities which are difficult to dissolve in molten electrolyte to form aged molten salt slag. The molten salt slag is accumulated at the bottom of the electrolytic furnace and gradually hardened, if the molten salt slag is attached to a tungsten crucible, the volume of the crucible is reduced, and finally, the electrolytic rare earth metal cannot be contained and the furnace is forced to be shut down; if the molten salt slag is attached to the bottom of the graphite tank, the furnace bottom will rise, the anode and the graphite tank are short-circuited finally, and the electrolytic reaction is abnormal, so that the molten salt slag generated in the furnace needs to be cleaned in time.

When molten salt slag is cleaned, the molten salt slag is pried down by a steel chisel and then fished out of molten electrolyte, a large amount of electrolyte (the main component is rare earth fluoride) is brought out by the operations, the content of rare earth in the molten salt slag is high, but the molten salt slag contains a large amount of impurities and has high density, so that the molten salt slag is difficult to be electrolyzed and used again, and the molten salt slag can only be used as waste to be delivered to a rare earth waste recovery enterprise to extract useful components again, on one hand, the waste of resources is large, on the other hand, the production cost of the dilute electrolysis enterprise is increased

Therefore, how to provide an electrolysis method capable of reducing the generation amount of the rare earth metal electrolysis molten salt slag and improving the primary electrolysis output is a problem which needs to be solved by technical personnel in the field.

Disclosure of Invention

In view of the above, the invention provides an electrolysis method for reducing the generation amount of rare earth metal molten salt slag, by which rare earth oxide materials added into a furnace are electrolyzed into rare earth metals, the generation amount of the molten salt slag in the electrolysis process is reduced, more rare earth metals are obtained under the condition of adding the same amount of raw materials, on one hand, the electrolysis recovery rate of the rare earth metals is improved, and on the other hand, the output of one-time electrolysis is also improved.

In order to achieve the purpose, the invention adopts the following technical scheme:

an electrolysis method for reducing the generation amount of rare earth metal molten salt slag is characterized in that the viscosity and the conductivity of molten salt electrolyte are adjusted according to the physical properties of rare earth oxides, and then corresponding current and voltage are adopted for electrolysis.

The invention adjusts the viscosity and the conductivity of a molten salt system according to physical properties, generally speaking, the higher the stacking density of the rare earth oxide is, the higher the viscosity of the molten electrolyte is required to slow down the sedimentation rate of the rare earth oxide in the electrolyte; the rare earth oxide has good wettability, the content of the rare earth oxide in the molten electrolyte is high, the conductivity is reduced along with the reduction of the rare earth oxide, the conductivity needs to be improved by adjusting the proportion of the molten salt, the rare earth oxide can be quickly dissolved into the molten salt electrolyte by proper viscosity and conductivity, the sedimentation speed of the rare earth oxide is proper, the rare earth oxide has sufficient electrolysis time, the generation amount of molten salt slag in the electrolysis process is reduced, and more rare earth metals are obtained under the condition of adding the same amount of raw materials.

Preferably, the physical property indicator includes bulk density or wettability.

The sedimentation rate of the materials with high bulk density in the molten electrolyte is high, the viscosity of the molten electrolyte needs to be increased, and the retention time of the materials is increased; the material with good wettability can be dissolved in the molten electrolyte more quickly, and the electrolytic reaction rate is high.

Preferably, the mass ratio of the rare earth oxide to the molten salt electrolyte is 100: 3-7.

The proportion of the molten salt electrolyte is based on the balance of the supplement amount and the consumption amount, and the proportion of the invention can give full play to the productivity of the electrolytic furnace.

Preferably, the molten salt electrolyte consists of rare earth fluoride and lithium fluoride, and the mass ratio of the rare earth fluoride to the lithium fluoride is 6-10: 1.

The proportion of rare earth fluoride and lithium fluoride is a key factor for adjusting the viscosity, the conductivity and the melting point of the molten salt, and when the proportion of lithium fluoride is large, the viscosity and the melting point are reduced and the conductivity is increased.

Preferably, the rare earth oxide is a light rare earth oxide.

Preferably, the rare earth fluoride is a light rare earth fluoride, and the rare earth fluoride and the rare earth oxide are the same or multiple rare earth metal elements.

Preferably, the voltage of the electrolysis is 3 to 4 times the theoretical decomposition voltage of the rare earth metal oxide.

The voltage is determined according to the theoretical decomposition voltage of the rare earth metal oxide, the voltage can generate voltage drop in molten salt electrolyte in the actual rare earth metal electrolysis production, and the electrolysis voltage is generally 3-4 times of the theoretical decomposition voltage according to the structural size difference of the electrolytic bath. The electrolytic voltage is high when the decomposition voltage of the rare earth metal is high, the current is the power input into the furnace in a reaction mode, and when the voltage is constant, the electrolytic power is high when the input current is high; when the current is constant, the higher the input voltage is, the larger the electrolytic power is. The current is in direct proportion to the conductivity of the electrolyte, and the higher the conductivity of the electrolyte, the higher the current is when the voltage is constant

According to the technical scheme, compared with the prior art, the invention has the following beneficial effects: the invention provides an electrolysis method for reducing the yield of rare earth metal molten salt slag, through the method, rare earth oxide materials added into a furnace are electrolyzed into rare earth metals, the yield of the molten salt slag in the electrolysis process is reduced, more rare earth metals are obtained under the condition of adding the same amount of raw materials, on one hand, the electrolysis recovery rate of the rare earth metals is improved, on the other hand, the output of one-time electrolysis is also improved, the yield of the molten salt slag for electrolyzing the rare earth metals is at least reduced by 30 percent, the electrolysis recovery rate can be improved by more than 0.5 percent, and the one-time electrolysis output of the rare earth metals is improved by more than 5 percent.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

An electrolysis method for reducing the generation amount of rare earth metal molten salt slag specifically comprises the following steps:

(1) the rare earth oxide was praseodymium neodymium oxide of company A, and its bulk density was 2.36g/cm³The praseodymium-neodymium oxide with high stacking density has high sedimentation rate in molten electrolyte, the viscosity of the electrolyte needs to be increased, and the lithium fluoride mixing proportion in the molten salt is lower limit; therefore, the praseodymium neodymium fluoride is added according to 4.5 percent of the mass of the praseodymium neodymium oxide, and the mass ratio of the praseodymium neodymium fluoride to the lithium fluoride is 10:1, adding lithium fluoride, and fully and uniformly mixing the three materials to obtain a praseodymium-neodymium metal electrolysis raw material;

(2) uniformly adding praseodymium-neodymium metal electrolysis raw materials into an electrolytic cell in batches, adopting metal tungsten as a cathode and graphite as an anode, and introducing direct current for electrolysis; under the condition of 1000 ℃, the theoretical decomposition voltage of praseodymium oxide is 2.37V, the theoretical decomposition voltage of neodymium oxide is 2.264V, the electrolytic voltage in production is 8.2V, the current is 5500A, and praseodymium-neodymium metal is obtained by continuous electrolysis at about 1050 ℃;

(3) the production is continuously carried out for one month, the production of the molten salt slag is reduced to 12.4 kg/month from the former average 18.2 kg/month, and the reduction amplitude reaches 31.9 percent; the productivity of the electrolytic furnace is improved from 4733 kg/Taiyue to 5006 kg/Taiyue, and the increase reaches 5.77%.

Example 2

An electrolysis method for reducing the generation amount of rare earth metal molten salt slag specifically comprises the following steps:

(1) the rare earth oxide adopts praseodymium neodymium oxide of company B, the stacking density of the rare earth oxide is 1.74g/cm3, the rare earth oxide belongs to an oxide with smaller stacking density, the sedimentation rate in molten electrolyte is slower, and the viscosity of the electrolyte can be properly reduced. In this embodiment, praseodymium neodymium fluoride is added in an amount of 3.7% by mass of praseodymium neodymium oxide, and then, the mass ratio of praseodymium neodymium fluoride to lithium fluoride is 8: 1, adding lithium fluoride, and fully and uniformly mixing the three materials to obtain a praseodymium-neodymium metal electrolysis raw material;

(2) uniformly adding praseodymium-neodymium metal electrolysis raw materials into an electrolytic cell in batches, adopting metal tungsten as a cathode and graphite as an anode, and introducing direct current for electrolysis; under the condition of 1000 ℃, the theoretical decomposition voltage of praseodymium oxide is 2.37V, the theoretical decomposition voltage of neodymium oxide is 2.264V, the electrolytic voltage in production is 9V, the current is 6000A, and praseodymium-neodymium metal is obtained by continuous electrolysis at about 1050 ℃;

(3) the production is continuously carried out for one month, the production amount of the molten salt slag is reduced to 11.9 kg/month from the former average 18.2 kg/month, and the reduction amplitude reaches 34.6 percent; the productivity of the electrolytic furnace is improved from 4733 kg/Taiyue to 5054 kg/Taiyue, and the increase reaches 6.78%.

Example 3

An electrolysis method for reducing the generation amount of rare earth metal molten salt slag specifically comprises the following steps:

(1) the rare earth oxide adopts praseodymium neodymium oxide of the company III, the dissolution rate of the praseodymium neodymium oxide in the molten electrolyte is high, the praseodymium neodymium oxide belongs to an oxide with good wettability, the conductivity of a molten salt system can be reduced in the electrolytic process, and the proportion of lithium fluoride in the molten salt can be properly increased to improve the conductivity. In this embodiment, praseodymium neodymium fluoride is added in an amount of 4.0% of the mass of praseodymium neodymium oxide, and then the mass ratio of praseodymium neodymium fluoride to lithium fluoride is 7: 1, adding lithium fluoride, and fully and uniformly mixing the three materials to obtain a praseodymium-neodymium metal electrolysis raw material;

(2) uniformly adding praseodymium-neodymium metal electrolysis raw materials into an electrolytic cell in batches, adopting metal tungsten as a cathode and graphite as an anode, and introducing direct current for electrolysis; under the condition of 1000 ℃, the theoretical decomposition voltage of praseodymium oxide is 2.37V, the theoretical decomposition voltage of neodymium oxide is 2.264V, the electrolytic voltage in production is 8.5V, the current is 6000A, and praseodymium-neodymium metal is obtained by continuous electrolysis at about 1050 ℃;

(3) the production is continuously carried out for one month, the production amount of the molten salt slag is reduced to 13.2 kg/month from the former average 18.2 kg/month, and the reduction amplitude reaches 27.5 percent; the productivity of the electrolytic furnace is improved from average 4733 kg/Tsunday to 4978 kg/Tsunday, and the increase reaches 5.18 percent.

Example 4

An electrolysis method for reducing the generation amount of rare earth metal molten salt slag specifically comprises the following steps:

(1) the rare earth oxide adopts praseodymium neodymium oxide of Ding company, the dissolution rate of the praseodymium neodymium oxide in molten electrolyte is slower, the oxide belongs to the oxide with poor wettability, the conductivity of a molten salt system is low in the electrolytic process, and the proportion of lithium fluoride in the molten salt can be properly reduced to adjust the conductivity. In this embodiment, praseodymium neodymium fluoride is added in an amount of 4.0% of the mass of praseodymium neodymium oxide, and then, the mass ratio of praseodymium neodymium fluoride to lithium fluoride is 9: 1, adding lithium fluoride, and fully and uniformly mixing the three materials to obtain a praseodymium-neodymium metal electrolysis raw material;

(2) uniformly adding praseodymium-neodymium metal electrolysis raw materials into an electrolytic cell in batches, adopting metal tungsten as a cathode and graphite as an anode, and introducing direct current for electrolysis; under the condition of 1000 ℃, the theoretical decomposition voltage of praseodymium oxide is 2.37V, the theoretical decomposition voltage of neodymium oxide is 2.264V, the electrolytic voltage in production is 8.7V, the current is 5800A, and praseodymium-neodymium metal is obtained by continuous electrolysis at about 1050 ℃;

(3) the production is continuously carried out for one month, the production of the molten salt slag is reduced to 12.7 kg/month from the former average 18.2 kg/month, and the reduction amplitude reaches 30.2 percent; the productivity of the electrolytic furnace is improved from 4733 kg/month to 4990 kg/month with 5.43% of increase.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.