CN1114365A

CN1114365A - Process for extracting high-valence cerium from ore leachate directly

Info

Publication number: CN1114365A
Application number: CN94106755A
Authority: CN
Inventors: 郭西林; 郭强
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-06-30
Filing date: 1994-06-30
Publication date: 1996-01-03

Abstract

The process for extracting high-valence cerium from ore leachate includes such steps as extracting 4-valence cerium into organic phase from diluted sulfuric acid leachate of F-C-Ce-La rare-earth ore concentrate calcined oxidatively, washing and back-extracting the organic phase as carrier to obtain solution of cerium sulfate (or nitrate, or hydrochloride), and preparing cerium oxide, cerium carbonate, coarse cerium (80-99.999%) or high-purity cerium, as well as fluorescent cerium (>99.99-99.999%). Its advantages include low cost, short technological route and high quality of products.

Description

Method for directly extracting high-valence cerium from ore leaching solution

The invention relates to a process method for directly extracting high-valence cerium from a dilute sulfuric acid leaching solution of rare earth ore concentrate of cerium-lanthanum fluorocarbon through oxidizing roasting, belonging to the field of rare earth hydrometallurgy.

The problems existing in the prior art are as follows: 1. the process is long, the yield is low, the benefit isnot high, and the raw materials are greatly wasted; 2. the purity of cerium oxide can only reach 99.75%; 3. thorium slag is stacked to cause pollution; 4. the process is difficult to control, and the adaptability is not strong in the process of preparing cerium oxide products; 5. the rare earth is excessively lost, thereby causing waste and pollution.

The invention aims to avoid the defects in the prior art and provides a method for directly extracting high-valence cerium from sulfuric acid immersion liquid of oxidized roasted fluorine-carbon lanthanum rare earth concentrate, and 80-99.999% of crude cerium and high-purity cerium products can be prepared in the same procedure.

The purpose of the invention is realized by adopting the following measures:

the invention relates to a method for separating trivalent rare earth from tetravalent cerium by firstly extracting all tetravalent cerium from dilute sulphuric acid leaching solution of oxidized roasted bastnaesium rare earth concentrate by an extraction method.

Mineral leaching acid is exemplified by sulfuric acid: and (3) in a 0.5-2N sulfuric acid medium, completely introducing high-valence cerium into an organic phase, washing and back-extracting to obtain a sulfate solution. For example, the mineral leaching acid uses nitric acid, hydrochloric acid and cerium salt as solution, and can be used for extracting to obtain cerium oxide, cerium carbonate, cerium nitrate, cerium oxide and other products. 80-99.999% of crude cerium and high-purity cerium products (or other salts) and more than 99.99-99.999% of higher-purity fluorescent grade cerium oxide products can be prepared in the same procedure; can also be used to prepare white cerium oxide products. If the grade of the cerium oxide is to be improved, the washing of the loaded organic phase is only strengthened once or fora plurality of times under the condition of not changing other conditions. If high-purity cerium oxide with the purity of more than 99.999 percent is to be prepared, the cerium oxide can be washed by 8-10N nitric acid (but the nitric acid is used before the nitric acid is used)Boiling or blowing CO₂Etc. to eliminate NO₂Reducibility of (c). The raffinate after cerium extraction contains 3-20% of cerium oxide, and is precipitated by double salt; ammonium bicarbonate or sodium hydroxide is converted into rare earth carbonate or rare earth hydroxide, which is dissolved in hydrochloric acid, and the trivalent rare earth solution with the adjusted pH value is fed into an extraction tank for extraction and separated into single rare earth to prepare a single rare earth product.

The invention has been in Shanxi Wen union operation rare earth factory, xi' an Wen military rare earth factory daily processing ore 1-3 tons, the flow is stable and reliable, the process is simple, the equipment investment is small. The total yield of the rare earth is more than or equal to 83 percent, and the yield of the cerium oxide (calculated by extraction) is more than or equal to 70 percent. The radioactive thorium and uranium are enriched and can be recycled, the environment is not polluted, the benefit is considerable, and the method is an ideal process flow.

The molecular formula of the pure bastnaesium-lanthanum rare earth concentrate is REFCO₃The crystal was hexagonal (a ═ 7.19 angstroms, c ═ 9.18 angstroms), and the theoretical amount of rare earth oxide contained was 74.77%. The rare earth content (after mineral dressing) of 35-65% of ore in Sichuan crown mineral in China is as follows:

La₂O₃/REO CeO₂/REO Pr₆O/REO

33％ 48～52％ 3～6％

Nd₂O₃heavy rare earth ThO in/REO₂

9～11％ 3～6％ 0.2～0.25％

The non-rare earth impurities are:

BaO SO₂F Cr Ti CaO Fe₂O₃

>-145.5-8.55-9<0.1<1%<2%, etc

The bastnaesite rare earth concentrate roasted in oxidizing atmosphere can adopt various inorganic acids such as: the sulfuric acid, nitric acid and hydrochloric acid leaching can be determined according to the type of the product and the selected process flow. Since the hydrochloric acid contains CI' root, has reducibility and high nitric acid value, the invention selects the sulfuric acid as the leaching acid, ensures the extraction yield of the cerium oxide, and is easy to operate and economical.

The roasting temperature of the bastnaesite rare earth concentrate is preferably controlled to be 550-650 ℃, so that the leaching rate of the rare earth existing in bastnaesite can reach more than 94%. After the bastnaesite is oxidized and roasted, most of cerium is oxidized into a tetravalence state, the oxidation rate can reach 92-95%, when diluted sulfuric acid is used for leaching, the tetravalence state cerium and fluorine ions form complex ions to enter an immersion liquid, and trivalent rare earth generates Rare Earth Sulfate (RESO)₄) Into the immersion liquid, the structural formula is presumed by calculation: complex of cerium with fluorine [ (CeF)₂(SO₄)]The fluoride ion is a complex which is not very stable, fluoride ions are released due to the change of conditions, and the fluoride ions are combined with trivalent rare earth to generate rare earth fluoride precipitates.

1. Self-shape release:

(1)

(2)

the problems of the reaction in the process flow are:

if the ore leaching stirring time is too long, rare earth fluoride precipitates can be generated.

This phenomenon can also occur if the immersion liquid is left for too long.

2. The tetravalent cerium encounters a reducing agent and fluoride ions are also released. Presumably, the reaction may be:

(4)

the problems of the reaction in the process are that:

the tap water contains chlorine radicals which have strong reducibility to cerium, so that not only tetravalent cerium is reduced into trivalent cerium, but also trivalent rare earth is generated into rare earth fluoride precipitate to be thrown into slag. In order to eliminate the influence of chlorine radicals, potassium permanganate is firstly introduced into the mineral leaching solution to destroy the chlorine radicals.

3. In the process of extracting tetravalent cerium, part of cerium fluorine complex ions enter an organic phase, and part of the fluorine ions and trivalent rare earth are released to generate fluoride precipitates which exist in a water phase and are difficult to phase separate and treat.

In order to eliminate the adverse effects caused by the three fluorine ions, the invention introduces the aluminum ions, so that the fluorine and the aluminum ions form a relatively stable complex. According to calculation and extrapolation, the structure of the complex is as follows:

AlFSO₄

the reaction formula in this scheme is as follows:

(5)

the complex has strong complexing ability, can extract fluorine ions from trivalent rare earth fluoride, and has the following reaction formula:

(6)

due to the formation of the fluorine aluminum ions, great superiority is brought to the process, the difficult problem in the process is solved, and the yield of the trivalent rare earth is improved.

In addition, nitric acid is introduced in the extraction process, so that the extraction rate is further improved, and the recovery rate of tetravalent cerium in the extraction process can reach 99%.

The invention has the advantages that:

1. the working procedure can shorten half time, the workshop operation workers can be reduced by one third, the yield is doubled, the rare earth loss can be reduced by one third, the yield is doubled, the total yield of the rare earth can be improved by 20 percent, and the method is an ideal flow with low investment and high benefit.

2. In the production process of the same procedure, 80 percent, 99 percent, 99.95 percent, 99.99 percent and 99.999 percent of CeO can be produced at any time according to the requirements of users₂And (5) producing the product.

3. The radioactive thorium is concentrated and can be recovered without pollution.

4. The production cost can be reduced by 10 percent, and if high-purity cerium is produced, the cost of the process of the invention only needs to be increased by 5 percent.

5. Short process, easy control and stable product quality.

6. Because the flow is reasonable according to the arrangement, the benefit can be improved by more than 50 percent (according to 99 percent of CeO)₂Calculated), if the efficiency is calculated according to the high-purity cerium, the efficiency can be improved by 5-10 times.

The following detailed description of the embodiments of the invention is provided in conjunction with the accompanying drawings:

the first embodiment is as follows:

adding 1.8 cubic meters of water into a reaction tank, adding 300 to 500 cubic meters of sulfuric acid (33N), adding 50 to 150 kilograms of aluminum sulfate and 1 kilogram of potassium permanganate under continuous stirring, heating to boil, gradually adding half ton of roasted concentrate, continuously heating and stirring, keeping the temperature at 90 ℃ for 10 to 60 minutes, cooling, clarifying and filtering, taking supernatant, extracting an organic phase (2: 1) according to the volume ratio, stirring for 1 to 20 minutes, washing the aqueous phase by 0.5 to 2N of sulfuric acid once, merging washing liquor into trivalent rare earth liquid, performing back extraction by 0.5 to 1N of sulfuric acid of hydrogen peroxide (conventional process), controlling the cerium oxide content in the back extraction liquid to be 100g/l, adjusting the pH value, directly precipitating by oxalic acid, converting into carbonate, sulfate, nitrate and the like, washing the organic phase by 1 percent of potassium permanganate (1N) sulfuric acid once, the next extraction was performed.

Example two:

the procedure of example one was followed except that the loaded organic phase was washed twice more,to obtain 99.99% high purity cerium oxide.

Example three:

the operation is carried out according to the first embodiment, the loaded organic phase which is washed once can be used, and then the loaded organic phase is washed twice by 8-10N nitric acid, so that high-purity cerium oxide with the purity of more than 99.999 percent can be prepared.

Example four:

the operation is carried out according to the second and third embodiments, the loaded organic phase washing liquid can adopt high-purity water, and the fluorescent grade high-purity cerium can be prepared by using a high-purity reagent.

Example five:

the high-purity cerium reverse solution prepared by the second and third embodiments can be prepared into a series of white cerium oxide products according to the white cerium preparation process.

The diluent of the invention can adopt carbon tetrachloride, kerosene, liquid paraffin and the like.

Claims

1. A method for directly extracting high-valence cerium from ore leaching solution is characterized by comprising the following steps: the method for directly extracting tetravalent cerium into an organic phase from a dilute sulfuric acid leaching solution of oxidized roasted bastnaesium rare earth concentrate to obtain trivalent rare earth and separate the trivalent rare earth from the tetravalent cerium, which comprises the following steps:

a: mineral leaching acid is exemplified by sulfuric acid: in a 0.5-2N sulfuric acid medium, all high-valence cerium enters an organic phase, a sulfate solution is obtained through washing and back extraction, and various inorganic acids can be adopted for mineral leaching liquid, such as: nitric acid and hydrochloric acid are used as cerium salt solution, cerium oxide, cerium carbonate, cerium nitrate and cerium chloride products can be prepared after extraction, and 80-99.999% of crude cerium and high-purity cerium products can be prepared in the same working procedure;

b: the roasting temperature of the bastnaesite rare earth concentrate is generally controlled as follows: preferably 550 to 650 ℃;

c: in order to destroy chlorine radicals and prevent trivalent rare earth from forming fluoride precipitate and losing the fluoride precipitate in slag, potassium permanganate and aluminum ions are firstly introduced into the immersion liquid;

d: the complex formed by the fluoride ion and the cerium is partially extracted into the organic phase, so that a proper amount of aluminum ion is added to the back-extraction solution of the washing liquid.

E: in order to improve the extraction rate, a proper amount of nitrate radical can be introduced into the extraction liquid;

f: the extraction tank body of the invention has no influence on the extraction effect by the extraction stages, so that single-stage and multi-stage extraction methods can be adopted.

2. The method of claim 1, wherein: in order to reach 99.99 percent of high-purity cerium oxide, the washing of a loaded organic phase is only enhanced once or for multiple times under the condition of unchanged process conditions.

3. The method of claim 1, wherein: preparing high-purity cerium oxide with the purity of more than 99.999 percent, washing the loaded organic phase washed once by the method of claim 2, and washing the loaded organic phase by using 8-10N nitric acid.

4. The method of claim 1, wherein: the preparation of fluorescent grade high purity cerium oxide can be carried out according to the method of claims 2 and 3, and the loaded organic phase can be washed by using high purity water and high purity reagent.

5. The method of claim 1, wherein: the high-purity cerium oxide liquid prepared according to the claims 2 and 3 can be operated according to the white cerium preparation process to prepare a series of white cerium oxide products.

6. The method of claim 1, wherein: the diluent can be carbon tetrachloride, kerosene, liquid paraffin, etc.