CN1120589A

CN1120589A - Carbonate method for conversion of sulfuric double salt of rareearth and separating cerium

Info

Publication number: CN1120589A
Application number: CN94116674A
Authority: CN
Inventors: 王易俗; 王鸿儒; 高才
Original assignee: YOUYI RARE-EARTH FACTORY BAOTOU CITY
Current assignee: YOUYI RARE-EARTH FACTORY BAOTOU CITY
Priority date: 1994-10-12
Filing date: 1994-10-12
Publication date: 1996-04-17

Abstract

The carbonate method for transforming double sulfate of rare-earth element and separating Ce features that the carbonate or acidic carbonate of ammonium or alkali metal as transformer reacts with the double sulfate of single or mixed rare-earth to generate rare-earth carbonate crystal and 4-valence Ce as soluble complex is in the solution. Through reduction or heating, cerium carbonate and high-valence cerium hydroxide are obtained respectively. The method has high direct Ce yield up to 90%, high Ce purity up to 99-99.95% and low sulfuric acid radical content less than 0.1% in the carbonate of rare-earth.

Description

Carbonate method for converting rare earth sulfate double salt and separating cerium

The invention relates to a rare earth sulfate double salt and a carbonate method for separating and extracting cerium, belonging to the rare earth hydrometallurgy technology.

In the existing rare earth hydrometallurgy, the rare earth-containing minerals are generally roasted and decomposed by concentrated sulfuric acid, the rare earth sulfate solution is obtained by water leaching, sodium chloride is added to generate rare earth sodium sulfate double salt precipitation, or rare earth sulfate double salt precipitation is generated by oxidizing and roasting the rare earth solution obtained by the rare earth sulfate leaching of bastnaesite and adding sodium sulfate. For further extraction and separation of rare earth products, the rare earth double sulfate salt must be converted into a hydroxide or a rare earth salt which is easily soluble in acid or water.

At present, sodium hydroxide solution is usually adopted to carry out strong stirring treatment in a strong alkali corrosion resistant reaction tank at about 95 ℃ to convert rare earth sulfate double salt into rare earth hydroxide, and the rare earth hydroxide intermediate product is obtained after washing and impurity removal. The method not only consumes a large amount of expensive caustic soda, but also needs a set of heating system, so the investment is large, the cost is high, the direct yield of cerium is lower than 70 percent, and the purity of cerium is only about 99.5 percent.

The invention aims to replace expensive sodium hydroxide with cheap carbonate, carry out conversion reaction in a common reaction tank at room temperature, and separate tetravalent cerium and trivalent rare earth in the conversion process to obtain pure cerium products, and provides a novel method for converting rare earth sulfate and separating cerium.

The purpose of the invention is realized as follows: ammonium or alkali carbonate, acid carbonate, etc. as converting agent are thrown into converting tank in excess amount based on theoretical amount, water is added to regulate slurry, and RE double sulfate salt in theoretical amount is added at room temperature (usually 15-38 deg.c) and through stirring to perform conversion reaction. After repeated gentle stirring and standing, trivalent rare earth carbonate is generated and crystallized and precipitated, and tetravalent cerium forms a soluble complex and is left in the solution. After filtering and leaching, washing for many times until sulfate radical in the rare earth carbonate filter cake is less than 0.1%.

Filtering and leaching to obtain filtrate [1]In a reduction tank, tetravalent cerium (Ce) is added with a reducing agent such as one or more salts thereof, hydroxylamine or one or more salts thereof⁴⁺) Reduction to trivalent cerium (Ce)³⁺) Generating cerium carbonate crystal, filtering and washing to obtain the cerium carbonate product. Filtering and leaching to obtain filtrate [2]Heating to 60-90 deg.C in a heating tank to generate precipitate, filtering, and washing to obtain higher-order cerium hydroxide [ Ce (OH)]₄]And (5) producing the product. The filtrate after cerium separation can recycle sodium carbonate and sulfate.

The invention is also suitable for the conversion and purification of any single rare earth sulfate double salt.

The invention is further described below with reference to the accompanying drawings.

The attached drawings are as follows: the technological process of converting rare earth sulfate double salt and separating cerium.

As shown in the figure, firstly, carbonate such as ammonium bicarbonate, ammonium carbonate, sodium bicarbonate, sodium carbonate or trona, sodium bicarbonate, etc. is mixed with Rare Earth Oxide (REO) in rare earth sulfate double salt and Carbonate (CO) in carbonate₃ ^＝) Or bicarbonate radical (HCO)₃ ^-) In the appropriate excess ratio:

namely REO: CO 2₃ ^＝＝1∶0.55～0.80

Or REO: HCO₃ ^-Putting the mixture into a conversion tank at a ratio of 1: 1.10-1.60, adding water for size mixing, then weighing the rare earth sulfate double salt filter cake (or size) according to the proportion, gradually adding the mixture into the conversion tank under the condition of full stirring, and reacting at room temperature. The chemical reaction formula is as follows:

in the formula: r is La³⁺、Ce³⁺......Re³⁺Single or mixed rare earth ions

M＝NH₄ ⁺、Na⁺、K⁺... ammonium or alkali metal ions are repeatedly stirred lightly and kept stand in the conversion reaction process, the filtration is carried out after the conversion is finished, the filter cake is leached and washed for a plurality of times by adding water until sulfate radicals (SO) in the rare earth carbonate filter cake₄ ^＝) Less than 0.1%. Filtering the filtrate [1]containing tetravalent cerium]Placing in a reduction tank, quantitatively adding hydrazine hydrate or hydroxy acid hydrochloride reducing agent to make soluble tetravalent cerium (Ce)⁴⁺) Reduced to trivalent cerium (Ce)³⁺) So as to form cerium carbonate crystal, and then pure cerium product is obtained after filtration and washing. Thefiltrate can be treated to recover sulfate.

If the transforming agent is sodium carbonate, the method for treating the filter cake obtained by transforming, filtering and leaching the rare earth sulfuric acid double salt is the same as the method for treating the filter cake. Filtering and leaching the obtained cerium-containing filtrate [2]]Controlling the pH value to be more than or equal to 11, placing the mixture into a heating tank, heating the mixture to 60-90 ℃ to generate cream yellow precipitate, filtering and washing the cream yellow precipitate to obtain high-valence cerium hydroxide [ Ce (OH)]₄]The product, filtrate can recover sodium carbonate for reuse and recover sodium sulfate byproduct.

Compared with the process flow of sodium hydroxide conversion, the rare earth conversion rates of the two are equivalent, but in the process of processing bastnaesite to separate cerium, the direct yield of cerium can be improved to about 90%, the purity can reach 99% or more than 99.95%, the equipment is simple, the investment is low, the operation at room temperature (only a small amount of heating is needed when the filtrate [2]is processed) is realized, the energy is saved, the source of the used conversion agent carbonate is wide, the price is low, the production cost is low, and the generated rare earth carbonate is easy to dissolve in acid and is suitable for further separation and extraction.

Example (b):

1. weighing 50 g of ammonium bicarbonate, putting the ammonium bicarbonate into a beaker, adding 30 ml of water for size mixing, and gradually adding 50 g of rare earth sulfate filter cake (containing 36.4 percent of REO and CeO on a dry basis) while stirring₂9.6 percent and the water content of the filter cake is 30.5 percent), the slow reaction is started, the reaction is obviously intensified andbubbles are generated after 10 minutes, and after 40 minutesGradually slowing down, standing, then slightly stirring every 60-80 minutes, standing again for several times, filtering and leaching to obtain a filter cake after about 5-6 hours, adding water, stirring and washing for several times to obtain rare earth carbonate, sampling and analyzing SO contained in the rare earth carbonate filter cake₄ ^＝Less than or equal to 0.1 percent. And (3) combining the filtrate and the leacheate to obtain 120 ml of a solution containing the four-stage cerium (the pH is less than or equal to 8), adding hydrazine hydrate (or hydroxylamine hydrochloride) to generate white precipitates, filtering to obtain filter cakes, and washing to obtain a cerium carbonate product with the purity of 99.0-99.9%.

2. Weighing 40 g of sodium carbonate, putting the sodium carbonate into a beaker, adding 100 ml of water to dissolve the sodium carbonate, and gradually adding 50 g of rare earth sulfate double salt filter cake (containing more than or equal to 28.1 percent of REO and total cerium CeO) after most of the sodium carbonate is dissolved₂8.51 percent of tetravalent cerium and 2.37 percent of tetravalent cerium) through stirring and standingThe operations of placing, filtering and washing the filter cake are the same as in example 1. Filtering and leaching the filter cake to obtain 120 ml of yellow filtrate (PH is more than or equal to 11), heating the yellow filtrate in a beaker to 60-90 ℃ to generate cream yellow precipitate, filtering and washing to obtain high-valence cerium hydroxide Ce (OH)₄Product, sampling and analyzing CeO-containing₂The ratio of/REO is more than or equal to 99.0 percent. Sampling and analyzing the obtained rare earth carbonate filter cake: the dry basis contains 34.8 percent of REO and total cerium CeO₂8.09％，SO₄ ^＝＜0.1％。

3. Weighing 40 g of ammonium bicarbonate, putting the ammonium bicarbonate into a beaker, adding 30 ml of water for size mixing, and adding 50 g of sodium cerium sulfate double salt filter cake (containing cerium and CeO)₂23.8 g) is calculated, the operation conditions are the same as the previous embodiment, 400 ml of water is added after 6 hours, the mixture is stirred and stood, and after the precipitate is clarified, the supernatant is poured out; repeating the steps for 5 to 6 times, finally precipitating, filtering and leaching to obtain a cerium carbonate product, sampling and analyzing SO in a cerium carbonate filter cake₄ ^＝＜0.1％。

Claims

1. A carbonate method for transforming rare earth sulfate double salt and separating cerium is characterized in that ammonium or alkali carbonate and bicarbonate are used as transforming agents, and are thrown into a transforming tank in excess according to theoretical amount, water is added for size mixing, the rare earth sulfate double salt with the theoretical amount is added under the conditions of room temperature and stirring, the mixture is fully mixed, and the rare earth carbonate is obtained by repeatedly and lightly stirring and standing, filtering and leaching, and washing a filter cake with water; filtering and leaching to obtain filtrate [1], adding hydrazine or salts thereof and hydroxylamine or salts thereof as reducing agents, reducing, precipitating, filtering and washing to obtain cerium carbonate; and (3) placing the filtrate [2]in a heating tank, heating to 60-90 ℃, precipitating, filtering and washing to obtain the high-valence cerium hydroxide. And finally, combining the filtrates, and recycling the carbonate and the sulfate.

2. The carbonate process according to claim 1, characterized in thatthe transforming agent carbonate is added in an amount (by weight) of REO CO₃ ^＝1: 0.55-0.80 or REO: HCO₃ ^-＝1∶1.10～1.60。